The anatomy of the honey bee


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The anatomy of the honey bee
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Snodgrass, R. E ( Robert E. ), 1875-1962
Govt. Print. Off. ( Washington )
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Full Text

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0.; HOWARD, Entomologist' and Chief of Bureau.

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L. 0. HOWARD, Entomologist and Chief of Bureau.




Agent and Expert.

ISSUED MAY 28, 1910.




L. 0. HOWARD. Entomologist and Chief of Bureau.
C. L. MARLATTr, A.fsi'tant Entomologist and Acting Chief in Absence of Chief.
R. S. CLIFTON, Exrecutive Assistant.
W. F. TASTET, Chief Clerk.

F. H. CHITTENDEN, inll charge of truck crop and stored product insect in r..tigations.
A. D. HOPKINS, in charge of forest inscct investigations.
W. D. HU'NTER, in charge of southern field crop insect investigations.
F. M. WEBSTER, in charge of cereal and forage insect in restigations.
A. L. QUAINTANCE, in charge of deciduous fruit insect investigations.
E. F. PHILLIPS, in charge of bee culture.
D. M. ROGERS, in charge of preventing spread of moths, field uwrk.
RIOLLA P. CURRIE, in charge of editorial work.
MABEL COLCORD, librarian.


E. F. PHILLIPS, in charge.

and experts.
ELLEN DASHIELL. preparator.
T. B. SYMONS, collaborator for Maryland.
H. A. SURFACE, collaborator for Pennsylvania.
J. C. C. PRICE, collaborator for Virginia.


Washington, D. C., October 19, 1909.
SIR: I have the honor to transmit herewith a manuscript entitled
"The Anatomy of the Honey Bee," by Mr. R. E. Snodgrasc, agent
and expert, of this Bureau. It embodies the results of detailed
studies made by Mr. Snodgrass and should prove of value as bring-
ing to the bee keeper reliable information concerning an insect of
such great economic importance, and aL1o as furnishing a sound
basis in devising new and improved practical manipulations. I
recommend its publication as Technical Series, No. 18, of the Bureau
of Entomology.
Respectfully, L. 0. HOWARD,
Entomologist and Chief of Butc(ua.
Secretary of Agriculture.

Digitized by the Internet Archive
in 2013

http://archive. o rg/detai Is/anatomyofhoneybe00snod


I. Introduction ..................................................... 9
II. General external structure of iiiects ................................ 10
III. The head of the Iee and its appendage-. ...-..-..................... 26
1. The structure of the head .....------------------------------............................. 2;
2. The antenrM, and their sene orans----------------------........................... "2
3. The mandibles and their gland ............................. ---------3
4. The probo-cis ............ ........................... -------------------------------------------.... 43
5. The epipharynx ......--------------------------................ ---------------.... 51
IV. The thorax and its appendages- ..................................------------------------------------... 53
1. The structure of the thorax.......------------......---------------------......... 53
2. The wings. and their articulation ....................-----------------------------...... 59
S3. The legs ...........................................--------------------------------------------...... i;
V. The abdomen, wax glands., and sting .....................---------------------------........ ;)
VI. Thealimentary canal and its glands ................................ 4--------------------------------
1. The general physiology of digestion, as-imilati m, and ex'roli,,n. 4
2. Thie salivary glands ..................................-----------------------------------...... 7
3. The alimentary canal ....--------------------------..................------------ 90
VII. The circulatory system .........................................-----------------------------------------.. 107
VIII. The respiratory svstem............................. ........... --------------------------------------------- -112
IX. The fat body and the oenocyte-...................................... ---------------------------------119
X. The nerous sy-temrn and the ey -------------------....--...-------.......-----... 1 2-
XI. The reprodur-tive system.........-------------------------...--------------- 130
1. The male organs ......................................----------------------------------------..... -I :2
2. The female organs .---------------------------------------......................................... 134
Explanation of the ,symbols and letters u-od on the illu-f rat ions--------........ 1
Bibl iogra phy ............................................. ---------------------------------------------....... 148
Index ...............................................----------------------------------------------..........--------... 151


Fi".. 1. Median longitudinal section of body of worker ....................... 8
2. Diagram of generalized insect, embryo ................................ 12
3. Example of generalized insect mouth parts ........................... 17
1. Diagram of generalized thoracic segment ............................. 19
5. Typical insect, leg ............................----------------------------------................. 2]
6. Diagram of generalized insect wing and its articulation ................ 22
7. Diagram of terminal abdominal segments of a female insect and early
stage in development of gonapophyses ............................. 25
s. Example of a swordlike ovipositor................ 25
9. Head of worker bee ................................................ 27
10. Heads of worker, queen, and drone .................................. 29
11. Median longitudinal sections of heads of worker and drone ............ 30
12. Antennal hairs and sense organs ..................................... 36
13. Mandibles of worker and drone ..................................... 40
14. Internal mandibular gland of worker ................................. 42
15. Mouth parts of worker .............................................. 43
16. Median section through distal half of mentum and b)ase of ligula of
worker .......................................................... 50
17. Epipharynx and labrum of worker .................................. 51
18. Sense organs of epipharynx .......................................... 52
19. Median longitudinal section of head of worker ........................ 52
20. Dorsal view of ventral walls of body of worker ...................... 53
21. Thorax of worker ................................................... 54
22. Lateral view of mesotergumn of worker ................................ 5;
23. Thoracic tf.rga of worker ............................................ 57
24. Upper :part of left, minesopleurum of worker. ......................... 58
25. W ings of Hymenoptera............................................. 60
26. Basal elements of wings of Hymenoptera ........................... 61
27. Median section through thorax of drone ............................. 64
28. I internal view of right 1)leurum of mesothorax of drone ............... 65
2!9. Legs of worker, queen, andl drone ................................... (17
30. ( 'laws and empodiumii of foot of worker .............................. (is
31. Tarsal claw.s of worker, queen, and drone ........................... 6!9
32. Lateral view of abdomen of worker................................. 7
33. Ventral view of abdomen of worker. ............................... 71)
3.1. Dorsal view of ;i abdominal stern of drone............................ 7()
35. Sixtl i al(oimiiial sternumn of worker, queen, and drone............... 72
36i. Snlidiiarzramnmatlic view of left side of sting of worker ................ 7.
37. Ventr l viiw if stling of worker. ...-............................... 7;
3s. SI-vt ini of sinm ll piece of wall of poison sac-.......................... 79
39. Se lI ii 'mis of alkaline glmnld of Stilig- ............................... 79
40. 1l).tails of st iiig of worker. ......................................... ,S1
-41. Tip of ,li( iInn, of worker with left side removed .................... S2


FI(,. 42. Alimentary canal of w orker .......................................
4:3. Detail, of pharyngeal and salivary glan(d.s .......................... .
44. IHoney stomach of worker, queen, and drone ........................ I
45. Longitudinal section of honey stomach and proventriculu.4 of qu[iin 17
4-16. Histological details of alimentary cai al of worker ................... 103
47. Dorsal diaphragm of drone, from one seg-niiift........................... 108
4S. Small part of dorsal diaphragm of drone ........................... 110
49. Pericardial chamber of one segment in worker ..................... II
50. Tracheal system of worker ........................................ 113
51. Tracheal system of worker ......................................... 117
52. Nervous system of worker........................................ 123
53. Brain and suboesophageal ganglion of worker ...................... 125
54. Horizontal section of compound eye and optic lobe of wrker ....... 127
55. Histological details of compound eye of worker ..................... 128
56. Reproductive organs of drone ...................................... 133
57. Reproductive organ and sting of queen ........................... 135




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F',;. 1 Lnn.- i i dinnl. median. v,.rti.i;l scti.,n ,4' pnlir' 1,oly' ,f I nr4k r. showing norvius system (OpL-7-GO g),
ilir;i.l ;and vntral diaphriirngm'm f abdoinmu (DI)ph and I'!),ih), and dorsal vessel consisting of heart

traclhal sNystem (TraSc, 1-10),
(Ht) and aorta (Ao).







The anatomy of the honey bee has been for veai's ,i object of miuch
interest to those engaged in bee keeping both for pl-;i.aiir'1 and for
profit. This interest is due not only to a laudable curi,)sity to know
more of the bee. but to the necessity of such information in order
to understand fully what takes place in the colony. All practical
manipulations of bees must depend on an under'-taiinding of the be-
havior and physiology of bees under normilnn and abnormal cir' iln-
stances, and those bee keepers who have advanced b)ee keeping most
by devising better manipulations are those, in general, who know
most. of bee activity. In turn, a knowledge of bee activity must re-t
largely on a knowledge of the structure of the adult bi,.
Studies on the anatomy of the bee have not been lacking, for
many good workers have taken up this subject for inve-tigation.
The popular dem.iand for such information, however, has induced
untrained men to write on the subject, and most accounts of bee
anatomy contain numerous errors. This is probably to a grater
extent true of the anatomy of the bee than of that of any other
insect. Frequently the ill'bit rations uled by men not trained in
anatomical work are more artistic than those iiusuially found ini paper-
on insect anatomy, and they con.-equently bear the superficial niiirk-
of careful work. but too often it is found that the details are in-
accurate. It has therefore seemed the right time for a new preta-
tion of this subject based on careful work.
The drawings given in the present paper are original. with the
exception of figures 12, 54. and 55, and have been prepared with
a thorough realization of the need of more accurate illustrations of
the organs of the bee, especially of the internal organs. Mistakes
will possibly be found, but the reader may be a.-siired that all the
parts drawn were -een. Most of the dissections, moreover, were
verified by Dr. E. F. Phillips, and Dr. J. A. Nelson, of this Bureau,
before the drawings were made from them. An explanation of the
abbreviations and lettering is given on pages 130-147.
It is hoped that the work will furnish the interested bee keeper
with better information on the anatomy of the bee than has hereto-
fore been offered to him, that it may provide a foundation for more
detailed work in anatomy and histology, and. finally, that it will be


4f -ervice to futture .-tiidents of the embryology and physiology of
thile bee. Withl this last object in view the writer has tried to sunim
ill) under each ending the little that is at present known of insect
phy-viology in order to bring out more clearly what needs to be done
in this subject.

Wheni we think of an animal, whether a bee, fish, or dog, we uncon-
-,ii:-lvy assume that it possesses organs which perform the same vital
funlictions that we are acquainted with in ourselves. We know, for
example, that an insect eats and that it dies when starved; we realize
therefore that it eats to maintain life, and we assume that this involves
tile possession of organs of digestion. We know that most insects see,
smell, and perform coordinated actions, and we recognize, therefore,
that they must have a nervous system. Their movements indicate to
us that they possess muscles. These assumptions, moreover, are en-
tirely correct, for it seems that. nature has only one way of producing
and maintaining living b)eilngs. No matter how dissimilar two
animals may be in shape or even in fundamental constitution, their
life processes, nevertheless, are essentially identical. Corresponding
organs may not be the same in appearance or action but they accom-
plish the same ends. The jaws mnay work up and down or they may
work sidewise. but in either case they tear, crush, or chew the food
before it is swallowed. The stomach may be of very different, shape
in two animals. but in each it changes the raw food into a soluble and
an assimilal)le condition. The blood may be red or colorless, con-
tained in tubes or not. but it always serves to distribute the prepared
food which diffuses into it from the alimentary canal. The situa-
tioni of the central nervous system and the arrangement of its parts
imay lbe absolutely 11llike in two organiillms, but it regulates tihe func-
tions of the organs and coordinates the actions of the muscles just
1he same.
Silence, inll studying the honey bee we shall find. as we naturally
eXl)ect to find, that it possesses moithi organs for taking uip raw food.
:ii alimenitaVry canial to digest it, salivary glands to futirnish a digestive
liqi iid, ai (0oitractile heart to keel)p the blood in circullation, a respira-
tr" sy.t.ii to fllurnish fre.h oxygen(l and carry off waste gases, ex-
vletory orgal-, for elimliinating waste substances from the blood, a
IervI.s s"stVAelm to regull tie :alld control all tlle other p )arts, and, filnally,
orgins Ito pIrdlice the rel)roddlictive elellenits from which new indi-
vidiual is are f'rmined to take tlie places of those that die.
''le tuid" of aiiatomily Ior tlhe strictillre of thile organs themselves
is- iliiily oilnniected vl with a stildyi of physiology or the life
fliilctioi. of i4 i ii:11i6111:. WlV lile l)hysiolog ia, i, s lllas iliterest ing
allid imp)(whiallnit .iilbject, anld, indeed. if, one seiise imiglit ie said to Ue



thile object of all anatomical ri,' iairch, yet tl' in m'e s-tl"dy of the
.,sttriicttire of the organs-1 alone, tlieir wonderful nel;ti':il adapti-
tioiL-. and their modificatiot-s in different aliIIIill- forlii- a IIIo-t fi-'i-
natillg field in itself, and besides tlli- it gives I- I11I ilsigh'it into 111
blood relation,,lilps and deulees of kiln lhip existing L tween tlie
multitudes of animal formn- found in nature. In the studv of coin-
parative anatomy we are constantly ,iirpri-,ed to find that t ii t.ti'e-
in different animals which at first sight appear to be entirely differ-
ent are really the same or'gais which have been simply clian ged in
a -.Iperficial way to serve some new plur'po. For example, the
front wing of a bee and the hard shell-like wing cover of a beetle are
fundamentally the same thing, both being front wings-thflat of the
beetle being hardened to serve as a protection to tle hind wing.
Again, tihe ovipositor of a katydid and the sting of a bee are identical
in their fundamental structure, differing in details simply because
they are used for different purposes. Hence, in the study of anat-
omy we must always be alert to discover what any special part cor-
responds with in related species. In order to do this, however, it
is often necessary to know the development of an organ in the
embryo or in the young after birth or after hatching, for many
complex parts in the adult have very simple beginnings in an imma-
ture stage.
Thus it becomes evident that the structural study of even one
organism soon involves us in the subjects of anatomy, physiology.
and embryology, and, if we add to this a study of its senses, its
behavior, and its place in nature, the field enlarges without limit.
The student of the honey bee realizes that a lifetime might be spent
in exploiting this one small insect.
The differences between animals are much greater on the outside
than on the inside. In the descriptions of the organs of the honey bee
anyone will know what is meant by the alimentary canal." the
' nervous system," or the respiratory system," but the external
parts are so different from those of animals with which we are more
familiarly acquainted that no general reader could be expected to
know what is meant by the names applied. Moreover, the bee and its
allies are so modified externally in many ways that. at first sight,
their parts look very different even from those of other iset'.
Hence, we shall give a preliminary account of the external structure
of insects in general, for it is hoped that the reader will then more
easily understand the special structure of the honey bee, and that the
application of the terms used will appear more reasonable to him.
Since all animals originate in an egg, the change into the adult
involves two different processes: One is groirth, which imnplie-
merely an increase in size, the addition of material to material; tlhe
other is development, which means change in shape and the produIc-


tion of a form with compnl)lex organs from the simple protoplasmnic
mass of the egg. The part of development that takes place in the
eggirhell is known as cmbr&yoide deeelopmcnt; that which takes place
-ub-eqitient to lhatching is known as postembryojic decelopme)nt. In
inse'ts there are often two stages in the postembryonic development,
an active one called the 1larc'al tayge and an inactive one called the
pil,,l stage. During the first of these the young insect is termed a
l,,,',,; dlllrinlg tlIe second, a pape. When there is no resting stage tlhe
imimatirite creature is often called a niymph. The final and fully de-
velope(l form is an adult, or Imago.
Since this ;paper is to deal only with the anatomy of the adult, the
attractive fields of embryonic and postemibryonic development must
1)e passed over, except for a few statements onil
Lm \ fundamental embl)ryonic structure, a knowledge
Nfth V t Ant of which is necessary to a proper understanding
.-r .-- 2At of the adult anatomy.
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i .Suni Xhen the embryo, in its course of development,
Lan yQ- /- Mix first takes on a form suggestive of the definitive
'._) --2. M..x
---L iiin-ect, it consists of a .series of -,eginents called
f ',,r.,,,..:f. rII//?( or M), dttcs. and :liowi, no differentia-
-.2L tion into liead,.thoracic, and al)doii final regions:.
0 j) L Typically, each s-eginmeit but tlhe first is p)rO vided
_u_. with a pair of latero-venta ral a np/.h lf/,s, 1hav-
0_ ing the form of small ro ldedl protiibe mra nice-.
S'J'lies(e appl)end;ages are of different size- aid take
on different sliapes in different parts of tlhe
0C body, for some of tliem are dletimed to formn ti'
,anten,, .solle the mouth parts, others the legs
An-" and perhaps tle cerci, wIiile tlie rest of tlieii
Fi.,;. 2.-Dia'gr.i.i of a r'la;iii very -nall and finally d i-a -ppeIar. Wliat
... irr lizi] insect em-
tI,\.. :..ii,,,,i.. the-.. we know of the emybivoloigy of ih-ect. is ased
loIntatioinf of the Iiil. .I 4 of
liihr:, ii-. :1,,, ahdom- 4111 l ie i dl--ervatio s of a il 1I)1ler of liell \wil)
inal ,.'_i-n-.. anud the liha'e worked mostly on tlie development of d(if-
"-{' llirll' ll ; ;I prllIl[r,. |. .1 l-' 11"
I I lferent species, Their ol-)servations are not all
likek. but this i prol ably due in large part to tlie fact that t]ie
(i+1rv1W ., of dilrerent ins-.ects are not all alike. Emlbryos have a ver\
p'rov(kij1g h]i=bit of skipping over (Ir joliittinig little and yet imi-
poirtant tliinig, in their de\velopmvet, bIlt fortunately tlhey do iiot
All Wiiit the s-iae tliinigs. Therefore bym puttilng togetlihei all the
reli able inform nation \we poscs-. \\e m;il muake up an idel l eiiibrlvyo
wici W0 would be typical of al iset-1. S( I a geer l ize d ebrioee is
rmepr,'elsted dli;ogn';im,;itic';lly by figilre "2.
'Tlie fir,-t -ix <,r -evVI, liieIuIt'lll(,rs very early beginl to unite w\ithl
onM ,notiel.1 a1 d continued to until tleir borders are lost. 'lThese
co,1-,li(lated elmrii"onie :s,9iuiemet- formi the lit'eal of tle a(dullt insect.



Observers differ concerning tlle fate of the -eveiith se'gri ienlt, but it
is most pro(l)alde tl:it ai part of it fuses wkth the i xth seg(rent, thu-
taking part in tlhe foriuation of the lead, and that a part of it fonii,
the neck or some of the neck plates of the adult.
The appendages of tliee first seveii seglilents form the anteuInn,
and mouth parts, except one or two pairs tli;it disappear early in
embryonic life. It is not certain that the first .-egmwent ever possesses
appendages, but from it arise the large compound eyes and appar-
ently also the upper lip, or labrum (Lm). The appendages of the
second segment form the feelers, or antennae (1int) of the adult,
those of the third (.2Ant) disappear in insects, but they correspond
with the second antennae of shrimps and lobsters. The appendages
of thle fourth segment form the mandibles (Mld). Those of the
fifth segment (Suin), when present, fuse with a median tonguelike
lobe (Lbn) of the following segment, and the three constitute the
hypopharynx, or lingua of the adult. The next pair (1Mx) form the
maxille, while the last (21Mx), or those of the seventh segment,
coalesce with each other and constitute the adult labium, or lower lip.
The bodies of the head metameres fuse so completely that it is
impossible to say positively what parts of the adult head are formed
from each. The last, as already stated, possibly takes part in the
formation of both the head and the neck. Some embryologists at-
tribute the plates which usually occur in this region to the last em-
bryonic head segment, while others believe they come from the next
segment following. Sometimes these plates are so well developed
that they appear to constitute a separate segment in the adult, and
this has been called the microthorax. If this name, however, is
given to the embryonic segment from which these plates are said to
be derived, it must be remembered that it is not "thoracic at all
and belongs partly to the head. The name cervicutm has been ap-
plied to the neck region with greater appropriateness since it does
not imply any doubtful affiliation with adjoining regions. What
we really need. however, is not so much a name as more 'information
concerning the development of the rear part of the head and the
neck plates in different insects.
The next three segments remain distinct throughout life in nearly
all insects, but, since.they bear the legs and the wings, they become
highly specialized and together constitute the thorax. The indi-
vidual segments are designated the prothorax, the mesotho ra, and
the metathorax. The legs are formed from the embryonic ap-
pendages (fig. 2, 1L, 2L, 3L) of these segments, but the wings are
secondary outgrowths from the mesothorax and metathorax and
are, hence, not appendages in the strict embryological sense.
The remaining segments, nearly always 10 in number, constitute
tlhe abdomen. The appendages of these segments, except possibly


thou-e of the tenth, disappear early in embryonic life in all insects,
excepl)t -omie of tlie very lowest species, in which they are said to fortli
certain :-mall appenid(lages of the abdominal segments in the adults.
An adult insect is often described as being divided into a head. a
thorax, and an abdomen., but this is not true in most cases. While all
in-ects con-ist of the-e parts, the divisions of the body are usually
liot coincidleit with them. The prothorax in the adult is separated
from the head by the neck and is very commonly separated from the
mesothorax by a flexible membranous area. On the other hand. tlie
mesothliorax and inetathorax are almost always much more solidly at-
tached to each other, while, in most insects, the metathorax is solidly
and widely joined to the first abdominal segment, though in the flies
these latter two segments are usually separated by a constriction. In
such insects as ants, wasps, and bees a slender, necklike peduncle
occurs between the first and second segments of the abdomen, the
first l)eilng fused into the metathorax .-o that it appears to be a part
of the thorax. This is the most distinctive character of the order
Hymenoptera. to which these insects belong.
The body wall of insects is hard on account of the thick layer of
chitin which exists on the outer side of the true skin. Chitin is a sub-
stance similar to horn, being brittle, though tough and elastic. It
gives form and rigidity to the body and affords a solid attachment for
the muscles within, since insects have no internal framework of bones
such as vertebrate animals have. The skin between the segments is
-oft and unclhitinized and thus forms a flexible ihtcei pemental mrem-
brane which is often very ample and, in the abdomen, allows each seg-
ment to telescope into the one in front of it.
The chitin of each segment is not continuous, but is divided into
plates called .s-1erlctes. The most important of these are a tc'r/ula
above and a sternuinm below, but, in the case of the thorax, these two
p1)lates are sel)arated on each side by another called the plcar-m, which
lies between the base of the wing and the base of the leg. Pleural
plates are somietiime.-, present als-,o on the abdominal segments. These
pricil)pal segnmiental plates are usually separated by membranous
lines, or spaces,. wliichi permit of more or less motion between them.
Sluc, lines are called .itui.res in entomology, though strictly this terni
s1loild lbe apl)plied only to the lines of fusion between adjoining parts.
The t(rga, )leuira, and sterna of each segment are furthermore
-1 bdiv'it)lcd into lstmaller sclerites. which Imlay b)e termed /,rgite plev-
r/,/.s, iad .s'./'.. re:petively. The stiihires between them are
-,,iii ,t iin 's 1- mIIIIlranols al.o, but ml.ost frequently have tlie form of
ipr(,-.-,(d lii., or narrow grloov)(es. In stichi cases they are generally
Wnoiliii mno re t11a t1e x1i e 'ial ii arlks of ridges developed on tlin
in,-idv of fli. od \\;wll to -vI'tiiiiei tlhv parts or to give ;attachiment
to 111(le.S Sinc( these siituir es are conIspicuiouIs miar:ks o1 I the out side



of an insect, they are usually regarded as mo'r)lpiologically impolr-
tant things in themselves, repre:-enting a telldlenlc(y of ill(,h tergliiim. pl,.i-
rum, or sternum to .separate into .-siale.r plates for .--nie reason. TIhe
truth about tliein would appear to be j.ii.t the opposite in mto-t .ase.
they are the unavoidable external mnark-, of an internal t1iclkeninr
and strengthlening of the plates. In a few cam-s they miay be the
confluent edges of separate centers of chitiiiizotion. Heiice. mvo)t of
tlhe sutiiral lines in insects appear to -ignify a lrwacing or olidiifying
of the body wall rather than a division of it.
Since the body wall of insects is continuous over all the -lrface it
contains no articulations of the sort that occur between the bone- in
the skeleton of a vertebrate. Although iii-ects and their allit.- be-
long to the class of animals known as the Articulata, yet an articu-
late articulation is simply a flexibility-two chitinous parts of the
exoskeleton are movable upon each other -imply by the intervention
of a nonchitinized, flexible, membranous part. While there are often
special ball-and-socket joints developed, the-e are always produced
on the outside of the membranous hinge and simply control or limit
the movement of the articulation.
The head of an adult insect is a thin-walled capsule containing tlhe
brain, the ventral head ganglion of the nervous system, the pharynx
and anterior part of the esophagus, the tracheal tube., and the
muscles that move the antennae and the mouth parts. Its shape varies
a great deal in different insects, being oval, globular, elongate, or
triangular. In some it is flattened dorso-ventrally so that the face is
directed upward and the mouth forward, but in most, including
the bee, it is flattened antero-posteriorly so that the face looks for-
ward and the mouth is directed ventrally. In a few it is turned so
that the face is ventral. The walls of the head are usually divided
by sutures into a number of sclerites, which in general are located
and named as follows: The moval)le transverse flap forming the
upper lip is the lab,'um. Above it is a sclerite called the dyi/peus,
which is a part of the solid wall of the head and carries the anterior
articulations of the mandibles. The clypeus is sometiime- divided
transversely into an anteclypeus (" clypeus anterior," "epistoma ")
and into a posft-r-lypels clypeusus posterior"). Above tlhe clypeus
is the front, a plate usually occupying the upper half of the face
between the compound eyes and carrying the antenmae. The top of
the head is called the vertex, but does not constitute a separate scle-
rite. The sides of the head below the compound eyes are often sepa-
rated by sutures from the anterior and posterior surfaces and are
known as the genme. The back of the head is formed by the occiput.
which surrounds the large opening or foremen maguimi that leads
from the cavity of the head into that of the neck. The parts po,-
terior to the gena. carrying the posterior mandibular articulations.



are sometimes separated from both the occiput and the gene and are
known as thle pvitjenw. In a few insects, especially beetles, one or
two median plates occur in the ventral wall of the head posterior to
the b.e of the labium. These are the rular sclerites. Finally, small
plate. are sometimes found about the bases of thle antennae and be-
twi\eii the ba-e- of the mandibles and the genT. The latter have
)beenil termed the trocharitius of the mandibles. The term epic) nhium
is often iiu-ed to include all the immovab)le parts of the head, but is
frequently applied only to the dorsal parts. Most of these selerites
preserve a pretty definite arrangement in the different orders, and
they are probably homologous throughout the entire insect series.
though they are in some cases very much distorted by special modi-
fications ad are often in part or wholly obliterated by the disap-
pearance of the sutures. Einbryologists are coming to the conclu-
tion that the sclerites of the head have no relation to the primitive
segments. The latter very early consolidate into a head with a con-
tinuous wall, while the sutures defining the selerites are formed
later. Some of the older entomologists were led, from a study of
the sclerites, to suppose that the head consisted of a number of seg-
ments, but it has been shownii that these anatomical segments do not
correspond with the embryonic ones.
The appendages growing from the front of the face are the
antennae (fig. 9A, Ant) or feelers" and consist of a series of joints
or segments.
At the lower edge of the face is the front lip or labr'm (fig. 9A,
Lm), behind which are the median epjhatryn.x, the paired mandibles
(lid) and maxillce, the mnediatn hypoppiarlynx,. and the iathim ori under
lip. All these organs together constitute what are known as tlie
'mouth parts or troplii. They vary greatly in shape and appearance
in different insects according to the nature of the food, )but their
ty pl)ical form is usually taken to be that shown by the lower insect.-
which feed on solid food and have biting mouth parts. Figure 3.
representing tlhe jaws and lips of the common black cricket, is given
as an example of generalized insect imoutil parts.
Tlie labrum (fig. 9.A, Lm) is usually a simple transverse flap in front
of the nmouith, b'iiig developed, as already shown, from a sinilarlv
situated lobe on the first segment of the e(bnll)ryo (fig. 2, Lm).
Tlhe epipharynx (fig. 19, A'pliy) is a sort of dorsal tongue, an d is
sithiated on the mmembrane leading into the mouth from be[)(hind thie
The mandibles (figs. 3A; 9A, Md) are typically formed for
bitilig, e)(,inig 1eavv' orrans situated immediately behind thlie lab1iin
an(1 workilqg sidewise (on a 11 iigf articilation with tlhe lIad. ITh(ir
clittilig edges are usually 0otlched and toothed, though smooth iM the
worker bee.



The maxillse (fig. 3 B and B) are complicated aplii(la.'ges in Ilici ir
typical form. Each Colsis()ts. of a principal piece called( the .f;,s-'i (Nt)
which is hinged to the head by means of a snialle.r b':-al pitce. the
cardo (Cd). Termiiially the stipes bears a- ti ouiler lobe, the git,'.
(Ga), and an inner lobe, the la,;u;a, (Lc). On the outer ,ide, at lHie
base of the galea, it carries a jointed appendage canlld1 the wm.:,i:;'ry
palpu.x (Pip).
The hypopharynx (fig. 3 C and D, HpIhy) is a med(lial. v'ciitral.
tonguelike organ, called also the liigua, situated either on the upper
surface of the labium or on the inemnbrane between this organ and the
mouth. It is de-
veloped principally
from a median lobe
of the head of the A
embryo behind the GIs Hphy
mouth (fig. 2, Lin), G8-.g'I 4 p
but some entomol- ,\- /v
ogists claim that it ,9
is compounded of Mt/ -"pg
this lobe and two
smaller lateral ones S Smt \
developed from the PipCd
appendages of the B C B
fifth embryonic
head segment (fig. Hphy S_ mt
2, Slin), the super- Gs--
ingquce. GP-l '-
miP91,11" W pig _Mt
The labium (fig. PgI -M
C and D) consti- I' D
tute theunde lipPip
tutes the under lip FG. 3.-Exaimple of generalized insect mouth parts, from
of the adult, but it common black cricket (Gcryll'i. pnursidrfinicu.s): A, man-
is formed from the dibles; B, B, maxille, ventral view; C, labium or second
is formed frm t maxillae, ventral view; D, labium, lateral view.
two appendages of
the seventh segment in the embryo, which fuse with each other. For
this reason it is often called the second maxillace. It consists of a basal
submen tum (Smt) bearing the menteiml. (Jt), which in turn carries
three parts, a median ligula (Lg) and two lateral palpiyers (Pig).
The latter support the labial palpi (Pip), while the ligula bears four
terminal lobes, of which the median ones are called the glossy (Gis)
and the lateral ones the paracglossa3 (Pgl). If we should cut the
labiium into two parts along its midline we should see that even in
the adult stage each half is very similar to one maxilla. The only
discrepancy to be noticed in the example given (fig. 3) is that there
22181-No. 18-10-- 2



it no maxillary palpiger, but many insects possess a corresponding
part in the nmaxilla, frequently distinguished as the palpitfer.
The neck or cervicum is usually a short membranous cylinder which
allows the head great freedom of motion upon the thorax. In nearly
all insects its lateral walls contain several small plates, the cer'ical
.,s.7/7..s, while, in many of the lower species, dorsal, ventral, and
lateral sclerites are present and highly developed. As already stated,
thie origin of these plates is doubtful. Some entomologists would
derive them from the prothorax, others think they come from the
last head segment, while still others think that they represent a
separate segment. Only pure anatomists, however, entertain this
last view and call this supposed segment the microthorax," for
enmbryologists have not yet reported a metamere between the labial
segment and the prothoracic segment. Most embryologists who have
studied the subject admit that some of the cervical sclerites may be
formed from the last embryonic head somite which carries the labium
and probably forms a part of the back of the head. Therefore, if
it is desirable to retain the word m'ic'otiora.x as a name for a true
segment, it can be applied only to this labial metamnere.a
The thorax, as has already been stated, is a distinct anatomical
region of the body rather than a division of the body. since it car-
ries both the legs and the wings and contains the large muscles for
each. Since the prothorax does not possess wings, it is not so highly
developed otherwise as the two wing-bearing segments, and is, indeed,
generally re(ldced in some ways, some of its parts being frequently
rudiment ary. Therefore we shall base the following description of
a typical segment on the structure of the wiing-bearing segments.
A typical thoracic segment, then, presents four surfaces, as does also
the entire body. These are a dor.,m above, a ,',n,(r' below. and ai
latt,s b on each side. From these names we have the terms dorsal,"
a In a foriner paper oni the thorax of insects (Proc. V'. S. Nat. Mius.. XXXVI,
1909, pp. 511 -5! 5) tivi writer lprb'ably drew a too definite conclusion on the
subject of the inici-r't1lrix." The origin of the lnlck schlerites lms prollhly
iI l*er vet 1e.en a- itailly (1.1served. 'mistiik :idil Kochl i (Ailer. Nat.. XXXVI,
1'i2. ppI'l. 1- -15), ill suijiiiii triziii. the seg ietll:lition of the head, accredited
tli, g iiiir :;l1(1 .d l -.(4clerites to thiet hilil] s.gilien t, but d i(1 not reco.-liize tie
I ;is Ifikiiihl. part in tihe f,'riiition of tihe true hed c;tll iSnle. Itilev. low-
4,\( r, in liis stiidy di' Ill< developlmie t of thie lihend (tf :1i cokro:cli (Aimler. Nat..
XXXVIII\ 1904, pp1). 777T 10), 4:itv,4 (Iint ill I/'fait tle lalii il se 1'rni :Ii piLrt of the tback of tilie b ,d Illa tliat tim posterior niris otf lle
Iildii rii, 1irc, d vri%(,d l'l"iiii it. I'lirner (Z )4)1. Alm., X X VI, lINl3, Il)l. 290l -:3151
;idl ('i'iui]il,,ii (I'ro.. A.n:id. N:it. Sci. l]iil:i... 19i9. pll ). :-54) eli('eve tihat the
<.,re vi,.il sI.h rites ;1r' i,1 ric',ed Pirinii pi;lly fl i tli t le protl cienl 'i segmIlent. The
n tIIii ll 1it tl, ry ciiivv i 41ltil' ;I .i pa;iri te stii' ll'i liet li(ln3 tl rit x," (eq( iv leontll
to illo' in i.:xillili'l sI'-P iii' iit of !lilr r'ent iti s. I;ts l i'll i*ltlli'i((4l lrinc i Nlly
lky V rln'ii l)tf ill liis ll tiil'r ,il \\rilil '"iis li<. i 'l ilopedil (ill d DIenl'lilllltet'al.
'l'li' l\'l <'ri i" l ri'4dil lli.s \\( i ld li'ir l ''r.liill.s lI kIlesii of no4 other t er"i
.-i plli'Id to lle Sidi1 ot (A' Ow P' liit ill lliis s, nse.



"ventral," and "lateral." The c'li(ii0iuis parts of the dorsiiui .mi-
stitute the tergym; of the venter, the ,4,,'n,,,,; and of the latws, the
ple itrum.
The tergum of the wing-bearing segments usually coinsist. of
two plates-a front one or true not",,# (fig. 4, N) carrying
the wings, and a posterior one, which the writer has termed the
postnotum or pseuidonotum (PN), having no connection with the
wings. The first is often more or less distinctly markl(d into three
transverse parts called the pmes.cutum (Psc), scutum (S,1), and *,*"-
tellum (Scl). In such cases the exposed part of the postnotiin is
called the postscwte1liim (Pscl). From either the anterior or the pos-
terior margin of the tergum, or from
both, a thin transverse plate projects t _PN
downward into the interior of the Sot SP
thorax for the attachment of muscles, Ap. ph
These plates are the phragmas (Aph
and Pph). The notum supports the .fV G" "x
wing on each side by two small lobes, 2P, \4P
P2t)" "' |3P
the anterior and posterior notal uwig 3p
proce.-sses (ANP and PXP). Behind PS
the latter is the attachment of the Ep
axillary cord (AxC) or ba:al ligament ep
of the wing. A large V-shaped ridge i_ xp
on the under surface of the notum hav- T
ing its apex forward is the "entodor- cx
sum." (A better name would be j
entotergum.) P s'si 1'
The pleurum consists principally of TaC
two plates, the episterin i,. (fig. 4, Eps) FIG. 4.-Diagram of generalized
and the epcnerum (Epm) lying before thoracic segment, left side.
and behind a vertical groove, the p/cural st,,ur, (PS), which extends
from the plei/ral coxal process (CxP) below to the pl, ,'ral waog
process (WP) above. The pleural suture marks the position of a
heavy internal ridge, the ploeral ridge or entopleurtm. The epi-
merum is connected with the post notum (PN) behind the base of the
wing. These parts occur in almost all insects. In some of the lower
ones another plate is present in front of the episternum which may
be called the pre(, u ti, (Peps) Lying along the upper edge of
a Objection may be made to the use of the term preeiisternuim on the
ground that it combiniies a Latin prefix with a word compounded of Greek ele-
ments. The same may be ur'ed against prephragma." "postp)hragima," pirt'-
paraptera," anid "postpa raipter.i," words introduced b1 the pr.sont writer in a
former paper on the thorax (Proc. U. S. Nat. Mus., XXXVI, 1909, pp. 511-595).
I1owever, we are barred froiim nakiiing up equivalent terms with the Greek pre-
fixes pro and ietai because these are used to designate the first and the third



tlie ,leiiriiii, and asotiated with thle under surface of the wing base
;tf',-cv,'al ,i;Ill plate- known as the pacaptera (P).a Two lie above
il,. pQi-.tcrnum in front of the pleural wing process and are the
,1;.s/ ij-1l /,,',ij1,crl( or preparaptera (1P and 2P), while one or
oc.: lionally two are similarly situated behind the wing processes
111d are the ri l ,ul j,.1 aapti-a or postparaptera (3P and 4P). The
prepaariptera afford insertion for the muscle concerned in the exten-
-ion and pronation of the wing.
T'hle cu.' (Cw), or basal segment of the leg, is hinged to the seg-
m1nclit by a dor-al articulation with the pleural coxal process (CxP),
and 1) by ai ventral articulation (TnC) with a plate called the trochan-
t, -(Ti) lying in front of it and connected above with the lower
end of the episternum (Eps). Hence, while the leg is of course con-
tinuouts all around its base. by means of membrane, with the body-
wall. its movement is limited to a hinge motion by these two special
articulation, of the chitin.
The sternum or ventral plate of the segment is not so complicated as
are the tergumi and )pleurum. It is often divided transversely into
thiIe, parts., however, and some authors say typically into four. These
parts have been named the presternum. (Ps), stern inm proper (S),
se gmteints of the thorax or their respective parts. Entomologists have already
t.stal1isiljd the system of referring a part to the front or back of any individual
seg int by the Latin plrefixes pre (or prw) and post as used in prescutum."
" presterl-Iilli." postsc-utelluimi," and "poststernell un." Furthermore, pre and
]IJtV ar sob ildliscriminiiately used in English combined with Latin, Greek, and
evii A.nglo-Saxoi Nwords that, they may be regarded as general property.
Itliice. in order not to sacrifice an anatomical system, which certainly needs
to be foistervdl in every way, the writer has preferred to sacrifice strict gram-
ni;infi';il rules by applying prc and po.t. regardless of the origin of the noun
in the ca;ise. to d4esignite interior and lposterior parts of the same segment. We
;ilr 1weier.L'n)in"in"
n1r- i r iim. u l -r( ern qs2
'l[4e 11,:111 I1,eeldistolomnil" ]]:Is ,,b en a;ipplied by Ilopkiins (llnl. 17, Pt. I.
f..lii. ;i se.ri-'., Bur. E'it.. U. S. Dept. Agr., 1909)) to a patrt of the meselpister-
Inuii tf D1) iIfiroctioii.-a -i late alpJiarthintly not liiiologous with the plreellisternlail
,"l.'ipicnt of Ill1 li'o ix inll priiiltive inlsects.
"The ii;lil' par.Irapterullm" is lRiken from Auld oiin*s term paripj)lhr (Ani.
,1.s Sri., I, IS24, pp. i97-1;.5, -11-4;- 2), ;ind its application, ais uste by tlhe
ii'-iilt \\wriilt', is la.1sed on Aiildoiii's definition givien inl his Chliapter ITT.
" r',,i..ivih'rif,,mrs. !i<'i r c',1 .sur lt 'I'or/ .r," '' w here lie says (p. 122) : Filially
1 l.-r' Ixisis ;i plio' but lilt, 1(W 1 devlloleid lhl seldom oblsierved, connected with
l,11, ili l itt*ristiiiun t;ill the wing. It is always sUlilioirted by the episternum
tiild is so,,n ,lill ,.s ljnIiigi d \l ruilally along its interior margin, or again,
Ix,,ii,,ingl_ 'fre lisss inll front of tlie wing aiili may leven cotmie to lie above
t0 li 1:is of ic' lit t.ri. At lirst \we desigillated this sclerite l)y the name of
IIl/,,pfl but' i"lli o1i1n ;.icolinit of its change of position reiathIe to tlihe wing base
w. io\" IWprefi r Ilin ii ii of 'ABA rTiT.:I:.'" Tei tirst )art of his (ldescri.jtion leaves
lil, 4o,,111 4lit i A liiiliii rfe.rrcd1 to tIl lii ti ilei'rlll late lenelleiatlh the front
of liUe wilig which is Lluatilly vury incunispicuous except i- carefully dissected


'ENERAI .XT, ItNAL '-,'I t"l' i 1; F INSI,'T". 21

A'f')JPivllb (Si) ;III(l p in-,ects a plate (x) occulr, ait ea'll .i1( of tl1i. plrc-trllm ,,or of Olie
sternuim which .elns to fill in line with the precpi-tIriiliii of tie
pleiitruiiii. Thi, ha. bl ,e'e varioii-ly ,.,1ed a ,/j't of t/ic ,'pri .,/, ,i', .
thlie co.,'fc r,,ii', a1n abX. ,i/f r.,,ii jplhf/, and the 1/,.,,f ri l lift ,r.1,i.
The inner "-iirface of the
sterin t iin carries a lar,,e / --
two-pronged process C ,/
called the f.'rci. or ento- Tb

This plan of structure
for the inesothorax and Tr
the metathorax prevails
throughout all insects.
The honey bee prol)ab)ly C111
presents the greatest de- Emp
1)arture from it, but even FIG. 5-TYjial insect leg.
i'ere the modification consi-sts principally of a suppre1.sion of the
sutures of the pleunru-n resulting from a condensation of the p)art-.
The leg (fig. 5) of an adult insect consists of a number of joints
or segments. It is attached to the body, as just described, by a thick

s,,iecimnens. In such preliarations. huiw+\vr, one finds there are in mi) st
c;.tses two sclerites here instead of one, and, furthermore. tha;it one or ,,r.i-
sionully two others are sinihirly situated beneath the rear p.irt of thle wln:z
base behind the pleunral wing pr icess. The pr,,seit writer has. therefore,
made the term iarailptera cover this whole row of little philtes. distinguish-
ing those before and those behind the pleural wing process by the designations
given above.
In the latter part of Aud(louin's definition it would seem that he may have
confused the rudimentary tegula as it exists in si,,me iusec(ts with the liarapte-
rum, but even this is not pr1)iable since he says it is always coinuected with
the episternum, which is never true of the tegula. In his dt-stcription 4-f th.,
thorax of beetles, Dyti.qct., Ctitrbu.>, Bitirf't.xix. and Citrculio, it is evident
that he regards the aniterior ullpel'r part of Tilie eliisternuln as the p)araptert-il
fused with the latter plate. In fact. in each case he definlitely states that siirh
is the case aind. in descrilbing Dytiscus ii',fl,.riif, he says (p. 4210) l'
eiisternumn, the pariapterum, anid the e'iniierum all fuse il sallyy :ilid constitute
a sipl))ort for the wings andil terguii." While Aiiudouin is undtilubtedly niis-
taken in this 1hmoilogy, especially in the mesithorax. he :it least showS
his "lparaptere" is a part of the pleurum. Ilence modern writitrs, sniili is
PaIckarld and Fols.'ii wl1ho nike the term ar;iiptera" s ynn Iimo fus %Nith
" tegui .l" are -ertl;ily Wr'4ing. The teguli is a dorsal sr:ile or it., rililintut
a;it the humeral a;gle of the wing, while the 1paralterumni is a co-existent sle-
rite below this part of the wing base. The present writer agrees with Coiiistock
and Kellogg. whi,. in their Eleiiients of Inse.t Ani athimy (first edition), le(lileo
the little sclerite in front of the base of thle win- in the locust, articulately to
the dorsal extremity of the elpisterinum, as the "p;inralteroni.." tough. ill this
insect there ;iare here really twu of these iiaraialiteral plates instead of onle.


1I 'il:i j :i It called the ,u.,' (( '.). Beyond this is a smaller joint
,IIl let I( t., tol,,iftlour (Tr), this i. followed )y a long and strong
Cfrilricthlt. thIe t' ,,,"p (F), which extends outwar(l from the body, while
1 )('1l1lig41 dtlwnwari'd fro(ll its ldi.tal(end is the long and slender tibia
(7T,), fuillo\wed finally by the foot, or tf ts.,N ( T7t'). The tarsus itself
c,,n-i-I- typi.;lly of five :-mall eventss of which the last bI)ear.s a pair
of i/c'. (C(a). Tiic iilte'r .--iurfaces of thle tarsal joints are often
priI ilt'<1 with -ilall c('-ions or pads called puirU';;. Those between
ulie <-li\\- ar' genePnally specially p)iromlinellt and are called the
,, /,il,, (L/ip). The leg relies greatly ill shape in different in-
-ct-t but -tsutlally preserves all of tliese parts. The segments of the
iars.'. however, Iare frequently reduced in Iltni)er.
T'le adult wing is a thin explanse of m, intrm, supported by hollow
br'iii .ii'g rods called o.,bs. It originates as a hollow outgrowth of
the body-wall, but soon becomes flattened out dorso-ventrally and tlhe

Tg 2Ax Sc

p V AiA cu2

Ie'1(;. 6.-Di] igram of generalize(d insect wing and its .i:ticuitlition to first )plate (\) of
tlit' ten~iini.

contained tracliee or air tubes mairk out tlhe courses of thlie veins.
Th'lse viins form various patter-ns in different insects, but they can all
be derived by modification from )one fundamental plan. This l)an is
show: (1iaZgral atically by figure 6. The first vein, wl1ich usually
formins the anterior margin of tlhe adult wingi, is the (.o.'ft (('). The
next xvin is the ./,e.iff. (Sc), which in typical cases divides into
two branicles-, (S,:' adil S.). Tile third and usually the prinucilpal
vein iV the ra.hi, (R). It divides dichotolnotisly into five b1anclies
(I? to It,), the a iterior branch of the first fork remaining single.
hI'll next \vein i- tlle rIli(/ (.1), which fo rl.s foulr l)ra''ches (.1/, to
.114). Thil i tith is- the t,.tU/.ix (Ci), whiich aga in is two-branched.
I"] I e (, II-ining ve i'ae :1alleti tl' an and ; allrl e desigia ate(l i1d(1i-
vidulally as the /it-t mi,,l (1 1), ../ (i, (2.l), etc.
Stvera'dl r/'.is.- I;/.s of (d'lnoii nl rectirreice should be noted. The
firt4 is -.itia:ltl ted :er flit' bae of tle wi i betlveen the (ostal and
.-IIll'.st,'l v'ils alld i.s lnlolwn as thi iimi'ni'l cro/ .t-tein. A second


occUIlr, betweelI the rnliii i and( the mielia near thle (,e'.ter of the \winll'
a1(d is called the 'adio- ,1',l cro.,,f-,',;,. Another one, ti iidio-
<,,b;,i1. is siimil;i nilv lol 1 ted (' bc en the media :1ij1l tI'li c(Ibitil-.
whlile a fourth, e;I.led the miiedian, occurs between the -econd and
third brwa iche- of the medlia. The areas of tlhe wing suIrface inu by the \veiii-. the cros--veiis, and the margins of the wing are lnowii
as the ,ec11..
A great many different iali's are applied by different ent4 miolo-
gists to the veins of the \vini^. both of the -0lie ani of liffi.en.t
iiineects. The nomenclat ir here given is the one first con -i-telitly
applied( by Comnistock and Needhami and now I-:el by ; lar' niumbler
of entomologist, working in different orders of in-vcd.
The wing is articulated at its base (except in nmavflie.- and dl,'agoll-
flies) to the anterior and posterior wing proces--:- of tihe notum
(fig. 6, ANP and P'NP) and to the wing process of the pleturn (fig.
4, WVP) by s-everal small articular sclerites called uxillarl's. Two
of these, the first (lAx) and the fourth (4Ax), form a hinge with the
anterior and the posterior notal wing proces-es, respectively, while
the second (2_Ax) articulates below with the wing process of the
pletirum, constituting thus a sort of pivotal element. The third axil-
1 fourth axillary-except when the latter is absent (as it is in nearly
all insects except Orthoptera and Hymenoptera), in which case it
articulates directly with the posterior notal process. The thin mem-
brane of the wing base may be called the axillary membrane (AxM.1).
On its anterior edge is a hairy pad, the tegdula (Tg), which is some-
times a large scale overlapping the humeral angle of the wing. The
posterior margin of the axillary membrane is thickened and may be
called the axillary cord (AIxC) or basal ligament of the wing.
The base of the costa is not directly associated with any of the
axillaries, but is specially connected by tough membrane below with
the episternal paraptera. The subcosta abuts against the end of
the curved neck of the first axillary. The radius is either attached
to or touches upon the anterior end of the second. The media and
cubitus are usually associated with each other at their bases and also
more or less closely with one or two mednm plates (m) in the wing
base. These plates, however, are not of constant shape and occur-
rence as are the articulating axillaries. The anals are generally
attached to the outer end of the third axillary, which acts as a lever
in the folding of the wing.
A few insects have a generalized wing almost identical with the
diagram (fig. 6), but most of them depart from it in varying degrees.
Few go so far, however, as the honey bee, whose venation is very
different, but yet the fundamental basal structure is the same even



here, as will be shown ill the special description of the wing of the
The abdomen consists alimono 4t always of 10 segments. There are
never any more than this number well developed in adult insects, and
if there are fewer the reduction is due to a modification of the ter-
miinal :-eigelnts to accommodate the external organs of reprod(uct ion.
T1e pzterior opening of the alimentary canal is at the end of tle
tenth -eorji)t, which carries also two small appendages at the sides of
tile anus. These are called the cerai (fig. 8,. Cer). In some insects they
are shlort. styletlike processes, in others they are long and many
jointed, while in many they are absent. The cerci are supposed to
be developed from the embryonic appendages of the tenth segment,
although, on tle other segments, these appendages disappear before
thle embryo hatches, except in some members of the lowest wingless
order of insects, which have a pair of cercuslike appendages on each
segment of the abdomen.
Each abdominal segment presents a tergum above and a sterniin
below; the former usually also reaches far down on the sides and
overlaps the edges of the sternum. In some insects one or more small
pleural plates intervene between the tergum and the sternum, but
the abdominal pleura are never developed in any way suggestive of
a thoracic pleurumi. Very frequently there is present ani upper
pleural plate, or cjpiplcrdte. adjoining the edge of the tergunm and a
lower, or ]i/pj)olpeCrdte, adjoining the edge of the sternum. Thle line
separating these two sclerites. however, is horizontal and(l can not
correspond with thle vertical suture of a thoracic l)leurImn between the
episternuim and the epimerum extending from the base of the leg
to the base of tlhe wing.
Tle most. complicated structures on the abdomen are the external
organs of reproduction. In the male these serve as clit.xp)n/ o/'i/1fm
1d1 take on a great, variety of forms in different sl)ecies. The organs
in the female form anl or'ipuo.tor and are of nmuch oimre definite and
Nroutauit struIict lire.
Tlhe ,,'t.pu;for (fig. 8), in its most perfect developlmelit, consists of
three lpai- of Jolly, choly apre-sed bla(lelike )1rocesses called
q.liipiJn/,. ,s. (1iG, 2,1 36('). Tli e.:e six pieces fit neatly together alnd
,Ill ah Irgi 1 icanis (if wvlhic thle fema I tle makes a hole ill thle
g"(101,nd mr ill the 1bark of a tree. or )punctures somte other insect., and
tliHII plJ:wevher <'e. ill Ole cvitY 111 tl ipoduiced. All interesting fact
in 1this (c(ionnectioni i-, thlat tilt- stinig of a wasp or bee is s1mimp1ly a mltodi-
fied ovipmoiitor. This ("111 1)I1 proved by a comiparison of thle organs
tl,,ci i i l%- or I" I ;Vli at _olE (f tl 'it 'r devh'v (lo)ltmeIt. Ea'li is formed fron1
-i\ lilt 4 1 ,ikc lpr," that rOW'l 0ilt 1"roit tilt' :tert';i of the eiglitli
a:nd mijllti aldniiij;l t'-giliicits of tlie larva or "oiuig soon after hatch-


9 r)

ing (fig. 7, 10, 2G, aid J,). At fil'st there is only ,I)(- pair (,f tllc.-.
processes on each of the two segriiments, but tho-e onl the ninth -0,11j
split each into two, thai producing two pairs o, iis .-,,'11,(ilit. l11
opening of the oviduct (OvO) is on the
eighth segenellt between the bi-(,, of tHe
first gol'-"
The ovipositor of the longhorned g'a--- ...
hopper, shown by figure 8, may 1be taken a-; OvO
a typical example of this organ. The ----_
median pair of gonapophyses on the ninth VIII - .G
segment (2-G) remain slender and fuse at IXr --
their bases into a small bulblike swelling
open below (ShB). The pair from the X -Cer
eighth segment (1G) form two long blade- /
like pieces, which fit by sliding articula- An 2G
FIG. 7.--Diagrami of terminal
tions upon the lower edges of the corre- abdominal -r nt of a fe-
sponding second gonapophyses (2G). The male insect and early stage in
first can therefore be worked back and development of gonapoph)1yes
(1G, and 3G), fi-ion
forth while they are braced and held in which is formed the ovi-
position by the second pair. The third positor of most insects and
the sting of wasps and bees.
gonapophyses (3G), or the outer pair of
the ninth segment (the left one in figure 8 is shown as if cut off near
its base), form two long flat blades which are closely appre-ed
against the outer surfaces of the others. In the detailed study of
the bee it will be shown how closely the structure of the sting corre-
sponds in every way with that of this ovipositor.


T AX Cer

T To

FIG. 8.-Example of a swordlike ovipositor, from a 1 liirhornfed grasshopper (Cono-
cephalus sp.), ilbii'4r.ting the fuindam:'nt:il similarity of structure with the -ting of the
bee, fig. .
Some entomologists have supposed that the original two pairs of
gonapophyses represeiit the embryonic appendage, of the eighth and
ninth segments, and they would thus establish a homology between
the ovipositor or sting and the legs and mouth parts. It has b)een
shown, however, that the true appendages of the abdominal s-egments
disappear in embryonic life while the gonapophyses appear muc.
later, during early nymphal or larval life. Furthermore, each pair



,f goiipophy.e.- arise.s in a median depression on the ventral side of
te 'egilent while tihe true appendages are latero-ventral. Hence,
tli cvideice is Very mirch against. this tlieory and the gonap)ophyses
appe '- to be special secondary processes of the body wall.
All iii:-ect- do not have ovipositors of the sort described above.
F"ie-. )evtles-. moth-,. amd( butterflies do not. Such insects simply
d411,) tliri. eggs from the orifice of the oviduct or deposit them in
i;i,--0- upon thei external surfaces of various objects. In some of
i1t. flie.-. however, the terminal segments are long and tubular and
entirely tl(c.,.,oped into one another. They are hence capable of
lwiIL, p)rotritl((d in the form of a long tapering tube having the opeln-
ii,-p of tlhe oviduct near the tip. This enables the insect to deposit its
eg'gs in dep crevices, lhut the structure is not a true ovipositor-it is
.-iliply tlie abdomen itself stretched out.
ITtW- tk breathe through a series of small holes situated along each
side of tlhe body. These breathing apertures are called spirachle's and
they lead into a system of internal air tubes called trachew(. There
are nearly always 10 spiracles present on each side of the body. Two
;re located on the thorax, the first between the prothorax and the
mesothorax, the second between the mesothorax and the metathorax,
while the other eight are situated on the first eight abdominal seg-
mne iits. Some embryologists believe that the spiracles of the pro-
thorax move forward in early embryonic life and unite with each
, ther in front of the hypopharynx to form the salivary opening, their
trachiee constituting the salivary ducts.
After this review of the general external structure of insects we
may proceed to a more detailed account of the parts and organs of
the honey bee.

The head of an insect, as already explained, is a composite organ
forii'ed of six or seven primitive segments, each of which, except the
fir't, typically bears a pair of appendages (fig. 2). Thlie anltelina are
developed flrom the enbl)ryonic appendages of the second segment,
the iniandibles fro n the fourth, the nmaxilla from the sixth, and the
1,0eond imlaxilla,, or labium, from tlhe seventh. The appendages of
tlie third segment disappear in early embryonic life while those of
the liffli ege nit,. \'ien the latter is present, fuse with a median lobe of the next segrineit to form the hypopharynx of
tlie. adult.
1. Till: MT ('T1'll': OF' Till: HEAD.
Tlie genIeral aplpeanr iiee an'd oilline of tlhe lead of a worker bee
;ire shiowni fr'mij befo re a nd 1el iind b1' figiire 9), A and B. In facial
view te lic (ad is trianiglar, with tlhe apex below. The side angles


are rounded and ca'ppe(d Ihy the lar'e ( ompoInd, eyes (E). IJ the
opl)o'ite direction the h (ad is, very iiiuch flaittv dl l. ti ,* -roto.-t di;ill,-
ter being 'cros\ i.e through the middle of the evi,. The fice is con-
vex, while tlhe p(),terior surface is somewhat hollowved, out and fit,
snuflgly upon the anterior end of the thoi-ax.
The large l\lei-tl eyes (fi. 9 A, E) ;ire .c(llte( the compound eyes,
because each i-1 composed of a large nim1ber of -'paIrate eYe elemiients
forming tlhe little liexagonal f,',,f.; visible on the siirtfice. All of
these facets togzetlier constitute the co(ronca, or tlie li i)ip;irent outer
surface of the eve, which in the bee is de-ivly clot1hed with vi( 1 hali I-.
The dark color of the eye is locatted in the deeper part) but I lI:.-, will
be described in the section dealing with the wervous system. On t lie

0Vx Vx ten
0c~ .-For

A 9B bPp
Ant -PrbFs

Pg 1Mk PgI
FIG. 9.-A, front view of head of worker bee with mouth parts (Pr6) cut off a 'short
distance from their bases; B, corresponding view of posterior surface of head.
top of the head between the compound eyes are the three simple eyes,
or ocelli (0), arranged in a triangle with the median ocellus in front.
Between the lower halves of the large eyes and near the center of the
face arise the antennae (Ant), each of which is inserted into a small.
circular, membranous socket. of the head wall, and consists of a long.
basal, 1-segmented stalk carrying a terminal 11-jointed arm movably
articulated to the stalk and generally hanging downward from it.
(In the drone the terminal arm consists of 12 joints.)Mt

The mouth parts are attached at the lower pat of the head, and
,-- / ,, "Lb PIP
Prb i 1Pl

conFsist. 9.A, front view of head of worker bee with mouth parts (Prb) cut off a s(ort)
distance frolaum (Ltheir bas) mesially.; B, corresponding view of posterior surfae of elongated.
top of tbladelike heorgans surrounding the protrusibl are tongue," which to-yes,
together constitute whatnged is commonly known asith the probmedian ocellus in front.
Between the lower halves of the large eyes and near the center- of the
face arise the antennae (Ant), each of which is inserted into a smal,'1
circular, membranous socket. of the head wall, and consists of a long,
baisal, 1-segrmented stalk carrying a terminal ll-jointed arm movably
articulated to the stalk and generally hanging downward from it.
(In the drone the terminal arm consists of 12 joints.)
The nmouth parts are attached at the lower- part of the head, and
(.011sist of the ??air!ibles (Md) laterally and the maxillme (.1x)
and labium (Lb) mesially. The latter two include the set of elongaite
bladelike organs surrounding the protrusible tongue," which to-
gether constitute what is commonly known as the proboscis (Prb).



Whien not in u-e the parts of the proboscis are bent back beneath
tlhe head. By referring to figure 9B. giving a posterior view of the
lhead. it will be -euen that thle basal parts of both the inaxille (St)
andI the lalbium (.lit) are suspended in a large hollow on the back of
thel craniumni. This may be called the cavity or fossa of the proboscis
(PI1F.x). Between the minandibles on the front of the head (fig.
9A) is a transverse movable flap. the labrum (Lm), attached to tile
lower edge of tlhe front wall of the head and constituting the upper
lip. The wolthi (.1th) lies behind the labrum and the mandibles
cloM: beneath it.
Below the antennal sockets is a transverse, slightly arched suture
(a) which turns downward on each side and extends to the inner
angles of the bases of the mandibles. The area bounded by this
suture is the ,.l/pce.s (Clp) and the suture itself may be called tlhe
c'lq// a'l s.turile.
On the posterior surface of the head (fig. 9B) is seen the pen-
tagonal foramen magnum (For) by means of which the cavity of
the head communicates with that of the thorax and through which
pass the nerves. (esophagus, blood vessel, and tracheal tubes. A
smalll rod (ten) inside the head arches transversely over the fora-
men magnum, cutting it. into a dorsal and a ventral half. At each
side of the foramen is a large pit (c) which marks the base of an
internal chitinous beamn of the head known as the mesocephalic pillar.
The opposite end of this pillar unites with the front. wall of the
head on the clypeal suture below the antennae, where it produces
another smaller pit (b).
Below the foranmen magnum and separated from it by a wide trans-
verse bridge of the cranial wall is seen the large fossa of the proboscis
(fig. 9B, Pr-bFs) having the shape of an inverted U. The side walls
of thi-, cavity are (hitinous and from their upper edges are suspended
the llaxlilIz1, while the base of the labium is contained in the menm-
brainous floor of the fosa,,,. The base of thle labium projects from the
ln'ad beneath or behind the mduth opening alnd its dorsal surface
foi-n, the floor of a preoral cavity surrounded by the bases of the
moutlh part and labrum.
It will be -.1n f'oiii the above description flat tlhe lead wall of the
bee contains- no sliture (except that bo inding the clypeus and the onme
Wini1 i'jN l.lvrawtvs the labrii' from the latter. Many of tlile higlr
in-icts hn-ave t1e ea id wall coipletely coitinIMIs, shio\ing no dio isioj
it all into cIeri e ih-. 1ut1, in foir. s a grasshopper or cockr1 acl
;,1d. in fact, iiii,-t of tIle lower insects, the liead as well as tlhe other
j;irt,' Id' tle ),,o14 i iii;de upo) of :I n mlh f plates, lhenc, this may
I. 1 rL'ir11dd1 ;i- the piiiiii iv. c(M lition. and it is presunledl that tlhe
Iiid:,i of thei. 6.. 11:i, ,,ei p1,(od.ced firo'mii MW wl o wall was divided
by stuIt'l'l- int ii n uni ml"r of d(i* til'nct paits. Tlierefore the different



rcg1i,,o." of the Ib,*,s head II:y I e, w iJ.iie', a,.,,-ordiilln to, to' .ic\ ith
which they cor'-epond i other in-''t-. 1` 1-. tle |I,1rt ()f thle I'F .-,
above tlie clypeii ; and et ,.\\c, the coil)oiI| d e.IY.- m1'1;y 6. c,,1114.1 III(.
front (tig. 9A. Ft), the pa rt, 'N Ie IIet compound eyve- the /"f" ("' ),
aInd the top of tlic hbetad the ,', .,
(V.,r). The areat on the back of the
liead around tlie foramen lialguIlnl i. E
,1a1y likewi!-e betennii(ed the occi(',;t ( al
S/,',,,, (fig. 9B, Oc) and the )parts be- L
hind the genav and the lower hal\e- e.'
of tlhe compound eye- the post,',,ffu,

The worker, queen, and drone differ iMdGl"
conspicuously in the shape and size of A
the lead, as will be seen by comparing
A. B, and C of figure 10. In these
drawings the front has been removed 2C /O
in order to show various internal- EIt
parts, whichli will be described later. -('
While the head of the worker (A) is "
triangular in facial view, that of the
queen (B) is more rounded and wider
in proportion to its length. The head MdGI/
of the drone (C) is much larger than
that of the female and is nearly cir- B
cuilar in outline. In shape the head
of the queen is intermediate between 0
that of the worker and that of the 1
drone, but in size it is somewhat
Taller than the head of the worker.
The eyes (E) of the worker and queen i
iare about e mual. but those of the drone .
are enormously enlarged and are
broadly contiguous on the vertex and
the upper pa rt of the front. On this
account the Iocelli (0) of the drone are'. 21l/
crowded down on the front. nearer the C
bases of the antenna, and the front rF. 10.-A, anterior view of hhad of
itelf is very much narrowed above, worker, with front, :et.nnnt,. aniid
te done.Ts of thed e con f piolei.i remo ie.d; B, correspond-
The antennae of the drone consist of in-, view of head of ,i,,un ; C, same
13 segments, while those of the females of drone.
have but 12 segments. The mandibles are large-t proportiountely in
the queen and are very small in the drone. Tlioe of the worker have
a smooth terminal edge. while this edge i- notched in the queen and
the drone. The parts of the proboscis are much longer in the worked

TillHE, I1..\A1 OF Till.; I AN.1D: ANI IT'- A.PI'I.M I A4;I.S.


;il 11( capable of muichl more action than in the queen and drone, which
are allmo.t entirely dependent upon the workers for their food.
Tlhe internal structure of the cranium may be studied best in a longi-
tiidinal M('tion of the head (fig. 11). In order to prepare a section
for tlii- ptirpoe imbed the head in paraffin and then carefully slice
Off o)he side with a sharp knife or razor just outside of the bases of
the landllible and antenna. Holding the remainder in the block of
paraffin or fastening the whliole in a dish of water or alcohol, care-
fully dis.ect away the soft parts from the head cavity so as to expose




- .Ten




x ip Rp
Mx PlIp EAp l~p









(' i

Mx Pip ;St EAp RAp


Lb PIp f
IV14;. I .*-A, l]Iiiilil iitlal section Iihroi i lIhead of worker lwtw%.e4i the incdinn pla11' au(I
outer ,.d.c, ,,r min.l iladii's (.1d) niin antennae (Ant) of left side. all internal so ft pirls
removed; B, 4 DiTI"',sl din' section Iliroughli head of (dron1 xc iPhy) and ir'-limiIi- (f1") are not rmlov.d.

lit' internal (,litinols p.irlts -liwn in figure 11 A and B. Tltiv.e
iLriit's. howvvv' ri p -'siei't a slice of the head taken from 1)etween thle
n('diii pl]: I(' and tihe outer edges of the ;Iijn(qeIIl and iaidlibtilar
1);i. s. of l he left 4i dl. Tlus oly tlie part-11 o) oe side of tlI Mid-
lin. ~r'. -lbo\\i. Figuurle A i.- from 0 a w(orke' and Figure B from a
drlet'. In tliO latter t114 pllIlrn.\x (nd s'so.)liagiis are retained ;indl
4liir Iivtec 1-, 14ot I'emiuovctd. F1i(Yre 20 shows tlu lieead cut. open from
;,l ;i11(1 t1e. 1111,t1i pl;r.'s rt,'1o'x l. A Siu'ii'ieii so cut and ),oild
: '-li(r( 1tin,4' iln ,iustii .-,odli or ,ot;lsli to 'reo'l1ve the soft parts will
1N4 fuid li i 1 Ilali' adijunt to this si41dy.



The principal parts of the internal skeleton of Itie head, or cd,-
cr/itiut, consist of two large, oblique, st ronigly chi6iioii.s bars forin-
ing a brace between the anterior and the posterior walls of Ilie lia'dl
(fig. 11 A and B, Ten, showing the pa ts on the left side only, and
fig. 19, Ten). These bars have been named by Macloskie (11S) the
viesocep)awi, pillars. As alread(ly pointed out the base of each \i-
marked externally by a conspicuolls pit (fig. 9 B, c) laterad of fhe
foramen magnum, and its facial end by a smaller pit (fig. 9 A. b)
in the clypeal suture near the upper end of each side of the latter.
The bases of these pillars are connected by the slender bar (fig. 11 A,
ten), already noticed, arching over the foramen magnum (fig. 9 B,
ten). This bar and the two pillars represent what is called in other
insects the tentorium. In the embryo the tentorium is formed from
tubular ingrowths of the head wall which unite internally and
assume different shapes in different insects. Since the air tubes of
the body also first appear as tubular ingrowths of the body wall,
some entomologists have supposed that the hollow tentorial in-
growths of the head represent the spiracular tubes of the head
which are, otherwise, lacking. However, there is not sufficient evi-
dence to support such a view as this, and there is no reason why the
tentorium should not have been originally designed simply to give
greater rigidity to the walls of the head where the latter support the
The usual form of the tentorium in the lower insects is that of an
X, with a large central body, situated like a brace across the lower
part of the head, having two of the arms directed anteriorly and
laterally and two directed posteriorly and laterally, and while the
former are said to be ingrowths from the mandibular segment, there
is some difference of opinion concerning the segment to which the
latter belong. Riley states that they are formed in the labial :eg-
ment of the cockroach and Carriere and Burger describe the same
thing for the mason bee. Other authors have ascribed them to the
maxillary segment, but they may, in later stages, lie in this segment
and thus appear to belong to it, while they originated in the one
following, having moved forward on account of the condensation
of the back part of the head. The tentorium of the honey bee.
consisting as it does of the two great mesocephalic pillars (fig. 11
A and B, Ten) and the small arched bar (ten) is so highly modified
that it is hard to see just how its parts are to be homologized with
the parts of an X-shaped tentorium. Probably the two pillars repre-
sent the separated halve, of the X, while the slender arch is an addi-
tional structure. In any case we have not enough evidence to war-
rant us in regarding the tentorial invaginations as modified trachea.
or their external pits as rudimentary spiracles. Similar proce-se_
extend inward" from the walls of the thorax to strengthen it or to
give attachment of muscles. Such pi'ocesses in general form the


cii. t-kileton allId are inidividulally called apodtenes. Those of the
liead c,.i,-titutt, the cnfto( r,,n11'mf/, those of the thorax the c toth orax.
TVie -ide walls of the fossa of the proboscis form two high, thin,
vcrticil plates. a.s >een from the interior of the head (fig. 11), in
fruint of the irie.soceplhalic pillars. The posterior edge (d) of each
of these plates is so much thicker than the rest of it in the worker
l;it it appears at first sight to be a separate rod. Its upper end
project, above the body of the plate as a free arm (e) to which is
artici1lated thle basal piece of the maxilla (Cd). It thus constitutes
the ),1..i1ninry .Awpe.nso'oam. (Macloskie includes under this term
b)tthli the arm of the cranial wall and the cardo of the maxilla.)
The head of the drone (fig. 11 B) presents, besides the parts de-
Tscribed, a thin plate (f) depending from the vertex of the cranium
along the line between the compound eyes.
Besides the-e apodemes of the cranial wall itself there are others
which project into the head cavity from the bases of the appendages
to afford points of insertion for their muscles. These are specially
developed in connection with the mandibles and will be described in
the discussion of these organs. Still other internal chitinizations are
developed in the walls of the pharynx, but these likewise will be
described(l later.

The antennit of the bee are the two slender, jointed appendages
movabl)ly attached to the center of the face. where each is inserted
into a circular lmeilbranous area or socket just above the upper part
of the clypeal suture. Their general shape and position are shown
by figures 9 A, 11 A, and 19, Ant. Each is seen to consist of two
a1;irt-, forming a prominent elbow with each other, and usually so
held that the first or proximal part extends outward and upward
from its frontal attachImieit and carries the other in a pendent posi-
tion from its distal end. The first part thus forms a basal stalk,
(called the scape (figs. 9 A; 19, Sep), consistillng of a single joint
inserted into tlle altelnnal socket of tlhe front by a prominent basal
(.()iiil( e Lenit toward the face. This articular knob is attached to
' tle rim of thle socket by a circle of membrane, but it is also pivoted
on a lslli(:ler pegliike process pr()j((ecting upward from the lower ed(lge
o)f the (, )kvt. IHence, while thie flexible immiinbrane allows each
;,i (nle1n:a to revwlv(e freely iM any direction, the latter is at the same
Sim,1i held fil1 rly ii pos,,ition by thie pivot. Thle alntenmile are moved
by special sei- of muscl(s inserted upon their bases within the liea(l.
Tle ,v('ci(1 ow (1 o it -Mal divi-ion of the ;aitemlina is cylindrical and longer
1l111 Ile fir'lt. frmiili4 a flexible fil, /li1m (fig. 9 A; 19, Fl) haingiing
duV'1ward from tlhe distal enLd of the scape. It i 1om)posed of 11


small joints in the worker an(d queen and of 12 in the ulrole. ''lThe
male antenna thus consists of 13 jointts in all, while that of tHlie fell'ale
has but 12. The first joint of the flagellum is freely articuIlated to
the scape, but the others do not have much play upon one another,
though they give flexibility to the flagelliiimi as a whole.
Each antenna is a hollow tube containing the large, antemial nerve,
minute extensions of the tracheal s-ystem, and the small muscles which
move the segments upon one another.
Popularly the antennae of insects are known as the feelers," be-
cause they are constantly moved about in all directions with a nervous
kind of motion as if the creature were feeling its way along by means
of them. In fact feelers" is a better name for these appendages
than the scientific term, for there can be no doubt that the .eme of
touch is very highly developed in them and that by means of them
insects acquire a great deal of information concerning their surround-
ings and their companions. Moreover, a large mass of evidence
derived from experiments shows unquestionably that the organs of
smell also are located upon the antennae in a great many if not all
insects, while some investigators believe that in some species they
carry in addition the organs of hearing.
The study of the senses of insects is a most elusive subject, and
becomes more so the more we ponder on the results of experiments.
In the first place, it is manifestly impossible for u-, to acquire any
real knowledge of an insects sensations, for what is to us an odor,
a taste, a color, or a sound may be something quite different to such a
differently organized creature. We can, however, by experiments
determine that some things which give us the senv-ation of an odor
are perceived also by insects when placed near them. Also it can be
shown that some of them distinguish substances of different taste in
their food, and likewise that they perceive movement and distinguish
the colors and in a vague way the outlines of objects. Furthermore,
it is known that some of their perceptions are more delicate than ours,
and that some insects at least see color where we see none. They may
even possess senses of which we have no conception.
Hence, while it can be positively stated that insects perceive differ-
ences of touch, taste, smell, sound, and light, and act accordingly, we
can not say what the sensations they acquire are like. In fact we
do not know that they have conscious sensations at all. What looks
like an action due to intelligent perception may be piurely a reflex one,
unaccompanied by any sensation. This of course involves the ques-
tion as to whether such creatures or insects are possessed of conscious-
ness or not-a question which can not be answered one way or the
Understanding, then, that our knowledge of insect senses amounts
only to this, that what gives us the sensation of light, sound, taste,
22181-No. 18-10---3



touch, or smell makes also some sort of an impression on the insect
and varies in degree arid kind much as it does in us, we may go on to
a study of the -enes located on the antenna.
Here, again, however, we are confronted by a difficulty, for while,
at first thought, it seems very easy to hold some strong-smelling sub-
stance near the antenna of a beetle, ant, or bee and observe the evident
displeasure with which the creature turns away, yet we may be en-
tirely wrong if we conclude that the insect smells the substance
that repel, it. Strong-smelling, volatile liquids may simply produce
pain in somie of the delicate nerve endings of the antennae. Some
other kind of a being, experimenting on our senses, might close up
our nose and mouth and prove that we smniell by means of our eyes
on observing the blinking we should perform when strong formalin
or ammonia was held close to the face. Furthermore, irritant gases
and volatile liquids affect the mucous membranes of our noses and
throats in a way quite independent from the odor that we perceive,
and there is no reason, why the same lnay not be true ot insects. As
pointed out by Forel, experiments on the sense of smell should be
iiiade with odorous substances that the insect meets with inll a state of
nature, which would be principally the materials it feeds on. In-
sects are indifferent to almost every mildly odorous substance not
used as food, which, however, does not prove that they do not smell
Again, in many cases, it would bI)e difficult to decide whether the re-
suilts of an experiment should be accredited to smell or sight. For
example, every bee keeper knows that hungry bees are attracted to
honey a long distance from their hives, and it would seem almost self-
evidelnt that they are guided by a sense of smell. Yet one might con-
tend that they find the honey by siglit, as, indeed, is claimed by a
iiiiinber of entomologists who have ilmade experiiiients o( the olfactory
powers of bees. "l'his (Iest. ion has been dlecidledl in some other insects
b y painting the eyes with soiie opaque siu)stance or by removing the
aitelnil'e, but the evidence is liot conclusive ol either side in the case of
Experiiients made by a large llnl)uer of competent investigators,
including Lubb(ok, Schiemenez, aid l orel, have l)roved conclusively
that the organs of the sense of smell il insects are located principally
on the anute ( na. The most interesting o(f thlese experiments arie l)er-
1haps those whim.ich Forel (1903) made ol ca(rrion-fee(ling beetles. IHe
froli(l the dead ;id )Intrmid bodies of a hed(gelhog and a rat infetst(ed by
;a sw;irnui of these 1w tles beloigigig to several genera. lie collected
more tfian 10 sl),eci mens from i hie carcasses and( removed their an-
(teT,,. ThenleI( placed them all at ()one place in the grass and moved
the d(ead bodies to ;i distafie of 28 paces from the beetles where lihe
concealed them in a tangle of weed(ls. Examination tlhe next day


revealed the fact that not one of the mutilated beetles had found the
c(arcasses. Repeated experiments gave the sallme riesults--iio beetle
without its antenna' was ever found on the dead animals, although at
each examination new individuals of the several species were present.
It might be supposed that the mutilation itself distracted the beetles
to such an extent that they did not care to eat. In order to test this
point Forel next cut off all the feet on one side of the body fromt a
dozen intact beetles and changed the location of the dead bodies again.
The next day five of this lot were found on the c;ir'ess's.
The same results have been obtained from experiments on other
insects. Ants distinguish between their comrades and enemies by
means of their antennal sense organs. Males of the silkworm moth
and many other moths and butterflies perceive the presence of
the females and are guided to them by an evident sese of smell
located on the antennae, for they fail completely to find them when
these appendages are removed, although one immediately recognizes
a female when placed in contact with her.
Similar experiments have been made on the bee, testing the ability
of the workers to find honey hidden from their sight. The results,
according to Forel, seem, curiously enough, to indicate that bees can
perceive odors but a very short distance from their heads. Forel
found that hungry bees in a cage would pass and repass hundreds of
times within a few millimeters of some honey concealed from their
sight by a lattice without discovering it. They ate it greedily, how-
ever, when the lattice was removed, though it had been perfectly
accessible to them all the time. Forel believes that "bees guide them-
selves almost exclusively by vision," and Lubbock holds the same
opinion. At the same time it would probably be a very difficult mat-
ter to convince many practical bee keepers that bees do not smell "
from long distances. It is a well-known fact that at times when nec-
tar is scarce bees are attracted in large numbers-to the houses of an
apiary where honey is stored, though, when the natural flow is suf-
ficient, they pay no attention to it. Tests of the olfactory :-ense should
undoubtedly be made under natural conditions. Bees inclosed in a
box with some honey concealed from their sight might not be able to
locate it in such close quarters though they might be smelling it all
the time. An odor in a room may so fill the air that it does not seem
to come from any particular direction and we ourselves would have
to exert our intelligence to discover its source.
While, then, it does not seem probable that bees have such limited
olfactory powers as some investigators claim their experiments indi-
cate, it may be accepted as proved that the organs of smell are located
principally on the antenna. It has already been stated that the sense
of touch also is very highly developed on these organs, although in a
less sensitive degree it is distributed over most of the other parts of


T H E N . ...... .... ..
the body. It is again specially developed on the palpuslike append-
ages of the sting. (See figs. 36 and 37. StnPlp.) Sections of a bee's
antenna show that there are
Hr, on its surface a great number
Mr /// of minute structures of sev-
SI 1,'/ Ctl eral different kinds, though
l,. t- all apparently are to be re-
C-0. garded as modified hairs,
a B which are undoubtedly the
sense organs. Now the diffi-
i-r, culty arises of deciding which
Hr of these to assign to the sense
'/#//,-Cd of touch and which to the
1,',. -// sense of smell. Different au-
thors have made such differ-
CI ent interpretations of the
I- C sense organs of insects that
the student attempting to get
Nv/ Nv D information on the subject
Pt from books must soon be dis-
hr couraged by their conflicting
; statements. But it must be
Hr--" Ct realized that only intelligent
guessing is possible where
C / -Pt several senses are located on
the same part. In the case of
the bee some authors have
E ascribed even a third sense,
E_. F ~that of hearing, to the an-
y/ tenna, but there is little evi-
Nv dence that bees possess the
N power of hearing. The senses
^--N\v t
, ,, ,of taste and touch are pos-
llio. 12.-Antennal hairs and sense organs of e and touch are pos-
(;fti'r Scihieiin-i'z). A. ex;imlp iif ian(eiin;il sessed by the lllntoith parts,
hairs (Hr) inileddhd in cuticle (Cll) but gil some entomologists think
having no nerve oinnIclion ; II, hollow hair t hn
,onlainin. ]irolnga tion id sp-tLTil cell (Cuh; that they contain oI'ganls of
C, D), straight antl curvedl tactile hairs cOn- smell also. Thus, the organs
IuavtAd with basal cells (Cl) and nrv, fibers
(\r) ; I.: cnitcl hair (HIr) sunken in a pit of sight are apparently the
(P1) of lie c'utih'h. prolbably an oifact ory l t a n b c
,rm;:n ; F, ,.losed sac shult in by thin dist' on lJloes that can IiOt be con-
jh,') on sxirf:ii, of .i'nna and coi t(ainin.L. a fusend witl sonime other sense.
,li.'lil.y',,, l ,,.i'..d cell ( / witl, ,,.,rI-Iv. con- rl'l le.,t accountt of the
liP, (1011l ( \ t?),
entelltiaiSil sense organss of the
1,.t. i- li;lt (of Suill111ilz (IS3), whose 1 drawillngs are Ihere reproduced
(fig. 12) anld whose text 1, tie Ibasi- of thei following descriptions.
Thei organ-, consia, as before .tated. of modified hairs and their basal



insertion, which ;ire conllectetld withe (.1ends of inerve fiber'.. Some
of thelil staid expoed oii the surface of the iliticl'e while others
are smiliikei into, or eiiti rely coneal.d withlili. pits of the iltegglliiiet.
In addition to the-e. there are two other kidi, l of -plcial hairs on
the antennae which have no nerve connections, while, fiiially, the ordli-
nary hairs. such as are found on all parts of the body, occur also oiji
them, especially on the scape.
The special hairs not provided with nerve endings are of two
sorts. One is a solid curved or hooked hair (fig. 12 A. I7r) which
is simply articulated into a socket of the cuticle (Ctl), while the
other (B) is hollow and is situated over a channel through the cuticle.
and contains a prolongation of a specially enlarged epithelial cell
(Cl) lying beneath it. These hairs can not be regarded as sensory,
since they have no communication with the central nervous system,
and it is not clear just what purpose they do serve.
The simplest sensory organ is a short, hollow, conical hair (C,
Hr) arising directly from the surface of the cuticle, over a wide
opening through the latter, and containing the end of a -vi-ory cell
(Cl) connected with a nerve fiber (.Vv), which goes into the main
trunk of the axial antennal nerve. A modified form of this organ
consists of a curved hair (D, 1Hr) set into a small depression over
the cuticular channel. Such hairs are probably tactile in function;
that is to say, by means of them the bee can perceive that its antennme
are in contact with some surface. The general integument is too
thick and dense to allow of any sort of delicate touch sensation being
communicated through it, but if one of the:-e movable hairs brushes
against an object the nerve within it must be at once stimulated.
Tactile or touch hairs are distributed especially over the outer sur-
face of the antennae and at its apex, but occur also scattered over
the other parts of the body and on the mouth parts.
Microscopic sections of the antennae reveal still other organs
which are not so apparent on the surface as the hairs just described.
One of thee is shown at E of figure 12. It consists of a small pit
(Pt) in the integument, widened basally, and having a small papilla
on its floor, in whose summit is the opening of a still deeper cavity
which also expands toward its deeper end. This inner cavity is
almost filled up by a conical plug (Hr) which arises from its floor
and ends just below the aperture into the outer pit. The plug con-
tains a thick nerve ending which arises from a ganglion cell con-
nected with the antennal nerve by a nerve fiber. Ten or more of
these sense organs occur on the terminal and the first three segments
of the flagellum. It is evident that each is simply a sensory hair
which has been doubly sunken into a cavity of the integument.



A.- l)before stated, it has been conclusively proved by several investi-
gators that bees perceive odors, and it is said that if the antenna,
are covered with shellac, bees can distinguish between distasteful
sub4-taiices only by means of the prol)oscis. Schiemenz and most
otlhr writers on the subject therefore conclude that the sunken cones
are the orgn-l. of smell, since, being below the surface, they could not
be organs of touch. Some other authors, however, among whom are
Cheshire, regard these inclosed cones as hearing organs. They sup-
pow- that the sound waves of the air enter the pit, as into an ear
cavity, and tlie-e set up a vibration in the cone which stimulates the
attached nerve ending. However, the appearance of one of these
con(es would suggest that it is too stable a structure to be affected
by so(iund wave.,, so the olfactory theory seems much more probable.
Finally, Schienienz describes the most specialized of all the anten-
iIl sense organs as a closed cavity (Pt) in the cuticle (('1) extend-
ing into the hollow of the antenna as a long. curved, tapering
Tlhis is shown at F of figure 12. A nerve (Vv) enters the lower
extremlity of the pouch, expands slightly into a nucleated ganglion
cell (C6), and then extends toward the top as a delicate spindle
drawn out into a fine taperiiig point. The surface covering of the
pit is a thin layer of chitin presenting several concentric light, and
d;iark rings su1rr iundin-g a central disc (hr). Sections show that this
appearance of rings is due to circular thlickenings of tle membrane.
and Schienmenz points out that the central disc is probably a modi-
fied hair, while the whole structure is to be regarded simply as a
modification of a tactile organ such as that shown at D witli the
iervve-ending and its ganglion inclosed in a sac. These organs are
rnmot abul(lat on tle antenah of the drones, whIere tlmev are situ-
ated, (especially oni the indler surface, sO clo)e together (hat but little
spae vis left between them for l]ie tactile hairs, wliile in the workers
and qu( ee 1s they are fnirther apart and are interspa:ced with many
tactile lhairs. Hence, whatever sense thel accommodate must be
much more highly developed in tlie males than in tlie females.
Scljieiienz described tlhiese (organ., as well as tlie sunken cones, as
orga.'s of smell. He ascribed only the senses of touchll aid smell to
tlie anltenliua', an:d both Che'.liire and Cowan concur in Iiis view of the
cli-ed1 pits. Arnhart (1o(w6) however, a rgumes tliat a1n organ of smell
m11-t h)e open to the air in order to permit tlHie ingress of odor par-
itl. S Il (' a o'ga; is co.t{itluted lby tlie sun ke, cones, but thle
clb.'d pit. hliavve not1hling to rec()m en11 d thleme for al olfactotvy fiunc-
tion. Aridi;t tIiillen further pinls ot tlhat llte Iburied( sacs, inclosing
:a delicately 1poi-ed nerve-edling aid covered by an external tym-
I;nnmi. lave :all thli mlcclihanic{'l elements of an organ of hearing.
IH fi( ially argu. tl.'it. 1,es must hear, since they produce special
:-[o, d :('i.Icli as ti, piping of lthe queens, and that, since no possible



organs of hearing have been discovered on any oilither part of the body,
some of the antenna sense organs nuisit 1,e auditory in fiinction. His
conclusion from these prenises is. of course, inevitable that the
closed sacs on the antennae are the hearing organic of the bee. What
invalidates the arguinient, however is the fact that no one lias- yet
produced any actiial evidence that bees,, perceive suind.
The following, then, may be stated as a general summary of the
evidence concerning the antennal sese and their -cvise or ran- in
the bee: (1) The antenna are highly sensitive to touch and are the
seat of tlhe sense of smell. (2) They are covered by :-veral kinds
of millnutie structures which are modified hair- containing special
nerv-e-endings. (3) By inference, it would eeni certain that these
are the :-ense organs, but we can only form an opinion, ba'-,ed upon
their struticture, as to which are tactile and which olfactory. (4) One
set of organs does not appear to belong to either of these categories
and their structiiie suggests an auditory function, but, in the al)-ence
of evidence that bees hear, the purpose of these organs must be re-
garded as problematical.


The mandibles (fig. 9 A, Md) are the dark, strongly chitinous
appendages of the head, commonly called the jaws. situated at each
side of the mouth, anterior to the base of the proboscis. In all in-
sects with biting mouth parts the jaws work sidewise, each being
attached to the head by an anterior and a posterior articulation.
They can thus swing in and out on a longitudinal axis in such insects,
as the bee, that carry tlhe head with the mouth directed downward,
or in the same way on a vertical axis in tho-e that carry the head
with the mouth forward.
Both mandibular articulations are of the ball-and-socket type,
although in the bee the socket is a very shallow one, the anterior
consisting of a condyle on the outer angle of the clypeus fitting
against a facet on the mandible, and the position of a facet on the
lower edge of the postgena receiving a condyle from the mandible.
The motion of the mandible is thus reduced to a hinge-joint move-
ment, and, on this account, insects can only bite and crush their
food; they can not truly chew it, since their jaws are incapable of
a grinding motion. Each mandible is, of course, as pointed out in
the introduction, really suspended from the head by a continuous
membrane between its base and the cranium, being simply a modified
saclike outgrowth of the head wall. The two articulations are pro-
ductions of the chitin on the outside of this mnemibrane.
Figure 9 A shows the location and shape of the mandibles (.lid)
of the worker as seen in a facial view of the head. Figure 11 A


show.- the appearance of the left mandible in side view, while the
right one is shown detached from the head in figure 13 A. The
Mandible. (dliffer conspicuously in size and shape in the three forms
of the bee as already de-cribed and a-- shown in figure 10 A, B, and C.
Thlat of tlie worker is hollowed out somewhat on the distal half of
its- inner face (fig. 13 A, 31[d) forming a spoon-shaped organ, the
1edire of which is smooth and rounded. The mandibles of both the
queenll (fig. 10 B) and tihe drone (C). however, are pointed at the
apex and have a conlspiLcuous subapical notch. Those of the drone
IA -are smaller than those of
1 t'" l ~eithlier form of the female,
\'" \1 but appear to be especially
i \' *\ '['i( K'
'^ \'l'jI, small on account of the
\ ^.\^.I,''lj \ great size of the drone's
Wcl I,,, \ head. The mandible of the
.: ^ \ ~worker is undoubtedly to
,k'j be regarded as the special-
\.i', .,.. ized form, since the notched
;, /; J?' mandible of the drone and
.f */ ~queen is of the ordinary
iHy'menopteran type. Both
,~MdC,'I.| thle drone and the queen
t a.l re, under normal circum-
j ....Ap & stances, fed almost entirely
EAp -- MdC.'p- by the workers, and they
EA) prolbablv never have any
S--Md use for their jaws as feed-
A ing organs. Thle queen
i M B 1 needs her -large, sharp-
1)ointed mandil)les for bit-
F 1i. 13.-A, right mi:ndil1e of worker, anterior ]l. e a out of the
viw, wit0 i .xtel,,1 r' and flexor muscles (l:JM('l L g e w O le
aind P.1cl) and iii:iinlililair *linds (1.14(1) at- thick wax cell in which
liinlc'd ; B, 4'(irI'r'-|l 1diiL, view id1 nmindiblle of le is re red, but the
ldron., with muscles cut off a short distance ', s rared, b1t te
i1,'-ir rases. drone, on the other hand,
beI)(ing re'aed in anl ordinary cell r-seinbling that of a worker, except
in ,izC. i-,a.-ilyv able to cut through the thin cell cap with his corn-
palratively weak jaw\s. The workers, however, have numerous uses
for tilh'i imanidibles as biting through the cell caps, eating
)oll'cI. a1nd modeling wa;x. The last is tlhe espl)ecial function of
hlte worker iii' Iildile. andl pr1ll)a,)ly it i- to accommodate this pur-
pom-e that it ha1- aw'qutired its specialized spoonlike shape.
E',l la t ilaldibl1e is. moved 1y two sets of muscles within the head.
Tl'e owilet.r te cn istitutes the c.tri,.,or mwis cle (fig. 13 A, EMcl) and
tle imier tle l..xor int,.,wc (RNJcl). Thle latter is the stronger of


the two, since all the work of the niaiiudible falls uponl it, the extnilsr
being used simply to opeil the jaw. Wlille these mnii.cles have( tilwi
origins o0! the walls of the iheia,1, they a:11' not illserted directly upo(I
the mandibles, but on large apodeines (fig. 13 A, EAp and RAp)
attached to tlhe edges of the mandible.
A gland opens at the inner margin of ,;ii.h inandible between
anterior articulation and the base(, of the apod(ine of the flexor
muscle (fig. 13 A and B, IMdGl). In the worker it consists of a
large sac covered with -ecreting cells lying withinj the front part of
the head between the clypeus and the compound eye (fig. 10 A,
IMdGl). These mandibular glands may be most easily studied by
removing the front as shown in figure 10 A, B, and C. In order to
do this, pull the head from the thorax and allow the prothoracic legs,
which will usually come off with the head, to remain attached to it.
Next mielt a small hole in the bottom of a paraffin dish with a heated
needle and fasten the head face upward into this, the attached legs
helping to anchor the head in the paraffin. Cover the specimen with
weak alcohol and by means of sharp needles remove the part of the
front on either side between the clypeus and the lower half of the
compound eye in the worker and drone and the entire front of the
queen. In figure 10 the whole front is removed in all three forms in
order to expose other internal parts of the head.
The mandibular gland (1IdGl) is of greatest size in the queen
(fig. 10 B), though it is large in the worker (fig. 10 A and fig. 13 A),
but it is reduced in the drone (fig. 13 B) to a very small oval sac,
which is hidden by another gland (2G1) in front (fig. 10 C). It was
first described by Wolff (1875) as an olfactory mucous gland (Riech-
schleinmdiisse) and was supposed by him to secrete a liquid which
was poured upon the roof of the mouth in order to keep this surface,
on which Wolff thought the olfactory organs were located, in a moist
condition capable of absorbing odor particles. There is absolutely
no evidence, however, of the presence of organs of smell in the mouth,
and furthermore, as pointed out by Schiemenz (1883), the gland
varies in the three forms of the honey bee according to the size of the
mandible, which is proportionately largest in the queen and smaIllest
in the drone. Of the three, we should expect the drone or the worker
to have the sense of smell most highly developed, and hence, even if
we did not know that the sense of smell is located in the antenna-,
it would seem more reasonalb)le to suippoe that the glands of the
mandibles are connected in some way with the functions of these
organs themselves.
The mandibles, as already stated, are used for eating pollen and as
tools for manipulating and modeling wax. Therefore, according to
Arnhart (1906), since the queen does not eat raw pollen, the product


of the mandibular glands must be intended for softening the wax
when it is worked in the jaws. The secretion of the glands is said
to be very volatile and strong smelling and to have an acid reaction.
It i: probably entirely po-sible that it may have a solvent effect upon
the wax. or even. whlen mixed with it, change somewhat the chemical
(c'l11p,-iti(on of this slbl)stalnce; in fact. some investigators claim that
the wax of the comb differs chemically from that freshly taken from
tfle w:i.x plates. Even this explanation, however, does not seem en-
tirely :atisfactory, for the only occasions on which the queen has any-
thling to do with wax i., when slhe gnaws lher way out of her cell after
lnatelliiig or bite-, her way into the cells of young queens in order
to sting, them. However, these occasional uses by tlhe queen of her
iiia1(dibl)e- appear to be important enough to maintain the large size
of thic, ort)rgaln- in the queen. al1d it may be reasonable to assume that
the ldemamidl upon their glands is likewise a large one when it does
occur. Yet the nmandibles of the
Ten b i queen are tootlied and sharp
Pge -L, pointed, which should provide her
d, C? with sufficient cutting power both
..-.-Dct to emerge from her own cell and to
Senter tlhe cells of other queens, and
S:o, on the whole, the opinion of
Schiemenz that the secretion of the
,Ilfflfdili maniblar glands is merely sali-
Ge 2MdG vary in function would seem to be
Frm. 14.-TInternal mandilui.i.l t;land the simpllest explanation and the
(2MIf(l') of worker, I lving na.iin 4t inner
wall of p,,stgen;, (Pi! l j .,id nin mOst logical one. However, an
(Dot) at inner tlg. f 1,;ase, of man- at'tual test should certainly l)e made
  • to determine whether the workers
    Imaiiipitlation of thle wax witl her imatldilbles prl)od)(luces any change in
    it, ad(1 to )discover whether tlhe queen si inply Iites hlier way inechan-
    icallyv tl1ro0irh0 the wall of tlie cell or at tlie same timlle softens the wax
    1)"v a s tchioll frill hler moumithl. "I'lle male iII ally case has little use
    for lhi, ,ait]dibles, aIId tlhe glands are so small thliat they must certainly
    Ine fiiictioiiless.
    A s-ec(id mandilular gland (fig. 14, J.JIdl() is present in the
    wo, rker. It coisists of a delicate, flattened., racemose mass lying
    a;'giiii-t l('e iiiterial face of the wall of tlhe fossa of thle proboscis.
    \Io'sc duct opens into tlhe mouth cavity at the posterior inner edge
    oft' i w l alit'lc. Tliis gla md was first described lby Bordas (1895) as
    the hifiii,,,,l ,,in Jnil(,r q. i witl! a -imilar gland iii the hBombida' (bumblebees) and in the Ves-
    pidl;t (yellow jackets) and to the maxillary glands of other Hy-
    iin'iiolph-I(. Nothing is known of its secretion1.



    The conspicuous group of monthii appen(lages in
    forming what is commonly known as the probos,-v"




    honey b6,,
    9 A, Prb),


    FIG. 15.-Mouth parts of the worker: A, tip of glossa, showing labellum (Lb), guard
    hairs (Hr), and ventral groove (k) ; B, same, from above; C, small piece of glossal
    rod (r) with adjining parts of walls (q) of glossal canal attached, showing; ventral
    channel (1) guarded by rows of hairs. D, parts forming the proboscis, labium in middle
    and maxillae at sides, flattened out, ventral view; r, cross section of glossa showing its
    invaginated channel (Luri) and position of rod (r) along its dorsal wall, and likewise
    position of channel (I) nf rod along median line within the glossal channel; F, end of
    mentum (Mt) and bases of ligula (Lg) and labial l)alpi (LbPlp), showing opening
    of salivary duct (.S'alDO), dorsal view; G, lateral view of proboscis showing parts on
    left side; H, lateral view of glossa (GIs) with its rod (r) torn away at base showing
    attachment of retractor muscles (2Rifcl).

    by means of which the bee takes up liquid food, consists of what cor-
    respond with the maxillah and the labiuni of insects that feed on solid



    food alone. By separating tlhe parts of the proboscis a little (fig.
    9 B) it will be seen that. while there are five terminal pieces present,
    three of them arise from one median basal sclerite (.It), the two
    wider lateral appendages (JMx) being carried each by a separate lat-
    eral basal piece (St). The median group constitutes the labium and
    the separate lateral parts the ma.cille.
    If the reader will now turn again to figure 3 C (p. 17), which may
    represent any generalized insect labium, and compare with it the
    drawing of the bee labiumn, forming the median series of parts in fig.
    15 D, hlie will at once be able to identify the parts of the latter. The
    principal elongate median basal l)late is the mentum (lit), the small
    triangular plate at its base is the /blmcntin (Smt). and the two
    jointed lateral appendages of the mentum are the labial palpi
    (LbPlp), each carried by a basal pmlpiger (Plg). It is only the parts
    of the bee's lab)ium that lie between the palpi which are actually
    different from those in the generalized diagram where they consist
    of the four lobes of the 7;fila(t (Gld and P/ql). But even here it will
    be seen that the two -,mall lobes (Pfl/!) in the bee's labium, partly con-
    cealed within tlhe bases of the palpi, correspond with the paraglossa.
    Hence we have only the long median appendage to account for and it
    is unquestionably the representative of the glo.xwfv (Gl.7) which are
    here filed together and drawn out into this flexible tonguelike organ.
    In fact, a comparison with the mouth parts of other Hymenoptera in
    which the elements are nmuch less,- modified leaves no doubt of this
    being the true interpretation of the bee's labiuim. It is simply an
    example of how nature constantly prefers to modify an already exist-
    ing part to serve some, new pu rpo1se rather than to create a new organ.
    If, then. we bear in mind that tlie slender median appendage of
    tlhe. bee's, l)abium rel)resents the glossa, of otlher insects, we mavy for
    conveieniece call it the "t ngue." as it is popi larlyv termed, or, since
    it is a single organ, there is probably )no grammatical objection to
    calling it, the g.ou. The wordl tongue." however, to use it prop-
    erly, Sliuld 1)e applied to the true U1 .iyi or /q/p)oph('ha.-nv (fig. 3 C
    and D, 1Hpl/iy) wl'ii h arise, fi-',il tlie upper surface of the labium.
    Many of tlhe older ei tomologists, adopting the notion from Kirby
    and Spence. who defined tlie term' in 1M'26., regarded the glossa of
    tlie bee s thie Immologom of tnhe Iingua in other orders. Even Pack-
    aird in hi-s Text-hook of Entomology calls the glossa the hypo-
    p)haryvnx." ('lie-lire namted it tlhe ligula," and his mistake has been
    l)(.rplet1)411ted *l Iv several oilither writers on bee anatomy, including Cook
    and C(Owai. The itini 1flhd propl)erly includes both the glossa and
    (lie p;'ragloss;e,, or should signify the basal piece from which these
    I'mr lobes ari-e (fig. :' C, Lfy). so that it can not be apl)plied to the



    The derivation of anatomical lnamie co'ints for nothing in their
    application-this must be determined by scientific 1isage and priority.
    Thus, f/lo.. i is the Greek word for tongule." )but it w'as- fir-t applied(
    in entomology to the median lol)es of the labium; linmu, is its equlliva-
    lent in Latin and was first given to the true tonigue or hypopharynx
    in insects; lig/da is a dimlinlltive derivative fro'in lingua and has
    come to be applied collectively to the terminal parts of the labium
    beyond the mentumn but not including the palpi. Hence, all these
    words mean the same thing by their origini-, but their anatomical
    applications should be carefully distinguished. In this paper there-
    fore the slender median appendage (Gls) of the labium will be
    called the glo.s'.sa, or, for convenience, the tongue, but with the strict
    understanding that the organ in question is not the true tongue.
    This latter should be called the hypopharynx," but, as will be shown
    later, it is absent in the bee.
    The glossa of the bee (figs. 9 B; 11 A and B, and 15 D, F, and G,
    GIs) is covered with long hairs which increase in length toward the
    end. The tip is formed of a small spoon-shaped lobe, the la&bc1,nm or
    boitton (Lbl), which is covered by short delicate processes branched
    at their ends (fig. 15 A and B, Lbl). The long hairs of the glossa
    are arranged in circles and the transverse rows of hair bases give
    the tongue a multiarticulate appearance. Surrounding the
    side of the base of the labella and forming two short subterminal
    rows on the ventral side of the glossa are a number of stiff, out-
    wardly curved, spinelike hairs (Hr). These hairs have been de-
    scribed as taste organs, but their appearance would suggest that they
    are simply protective spines guarding the delicate tip of the tongue.
    Between the two ventral rows of these spines is the termination of
    a groove (A, k) which extends along the midline of the under sur-
    face of the glossa (D, k) to its base (fig. 9 B, k). The cleft of this
    groove is covered by two fringes of converging hairs whose tips are
    inclined also toward the tip of the tongue.
    Let us now return to a study of figure 15 D. The series of lateral
    pieces as already explained are the maxille. A comparison with
    figure 3 B representing a generalized maxilla will show that these
    organs in the bee have suffered a greater modification than has the
    labium, but the parts can yet be quite easily made out. The main
    basal plate (St) is the combined tp.s' sfbgale,. and palp;/fer, the
    basal stalk is the caldo (Cd), and the little peglike process (MIxPlp)
    at the outer end of the stipes is the greatly reduced nmaxvliary palputs.
    Hence, we have left only the terminal bladelike lobe (J/x) to account
    for, and it is evident that it must be either the galea or the lacinia
    (see fig. 3 B, Ga and Lc) or these two lobes combined. Here again
    a comparative knowledge of the mouth parts of Hymenoptera comes



    to our aid and shows clearly that the part in question is the outer
    lobe or higher member, of the order and finally disappears.
    The base of the submentium is connected in the bee with the upper
    ends of the cardiiies by a flexible, widely V-shaped band, the loriun
    (Lr). The po(terior angle of the subinentum rests in the apex of the
    loriiiii. while the tip-s of the loral arms, are movably articulated with
    the distal ends of the cardines. The name b" lora was given to this
    structiire by Kirby and Spence. but "lorum "" is more correct, since
    this is the Latin form of the word (meaning a thong or lash). Some
    recent entomologists have spoken of the structure as consisting of
    tvo rods, thus making the word do duty as a plural, but the thing
    itself is all one piece. Cheshire and some others have incorrectly
    applied the name to the submentum.
    The lorum is peculiar to the Hymenoptera, and the reason for it
    is clear when we examine the attachments of the parts of the proboscis
    to the head. As already stated, tlhe inaxillhv and labium are sus-
    pended in a large cavity on the back of the head which may be called
    the fo..i, of tMlc probo0,is (fig. 9 B, PrbFN). The maxillah are articu-
    lated by their cardines (Cd) to thlie' naxillary siispensoria (fig. 11
    A, e) at the upper edges of the side walls of the fossa. The labium,
    on the other hand, is not attached to the solid walls of the cranium
    but is slispen(led in the niembranolls floor of the fossa. This is to
    afford it freedom of movement diiring feeding, bltlt. in order to
    give it more substantial support and to make the regulation of its
    motions possible, the subinentum is slung to the ends of the cardines
    by the lorum.
    The terminal lobes of the labium and maxillk when not in use
    are ordinarily folded down beneath the hliead against tlhe mnentuml
    and stipites (fig. 19). When, however, tlie bee wishles to imbibe a
    thick liquid such as hioiiey or sirtip in large qpiatity, these pl)arts are
    straigthttened out aid held close togeliher so as to form a tb)e between
    tl,,e leading into the mouthl, tlhe terminal joints of the labial palpi
    alone diverginig from th1 rest (fig. 11 A).
    Tie action of tlhe mouth parts while feeding may be observed quite
    easily if son e bees are given a small amount of honey and then
    \v;itcle(,d throIuglh a leis while they are eating. A most coni'enieint
    i ieti(od i, to p)t ait few workers in a small screen-covered cage, such
    Is ;'ire -,sed for quee, nurseries. spread a siall drop of honey on tlihe
    wire, the, place tle cage unlder a silp)le microscope. It will be
    s.,enNI that the Imaxilla' are held almost stationary bIit thliat thlie base
    of tli. labil umi slides back aild forth between the maxillary bases
    \\ith : ver' regular to-and-fro movement, t as if the honey were being
    eitiler 1 1111ud or sicked 1,p1) into t( 111m)tih. It is probable that there
    is a sucking force exerted by tlhe ph)larynx (fig. 11 B, Phy) but not



    by the honey stoinach (fig. 44, IIS), whlichl latter, a, ('1eIiirc', N,-
    marks, could no more suclk hioney through thle '-jophlagii- tlan a
    balloon could suck gas from a pipe. Ti liquid undoubt(dlyh rli
    up the temporary tube between the blade' of li mouth parts fir-t
    by capillary attraction. but it nlt be ,greatly as-isted along its way
    to the mouth by the retraction of the labiumn. Tlie load brought qp
    when tli.-s is pulled back is thenii sucked into the mouth by the
    pharynx while the labium immediately goes out again after more.
    It acts thus as a -ort of mechanical feeder and this function is prob-
    ably derived from the lapping motion of the under lip in wasps and
    The mentum (fig. 15 D and G, Mt) is hinged freely upon the
    submentum (Smt), the latter, as already described, is set into the
    socketlike angle of the lorum, while, finally, the arms of the lorum
    are articulated to the distal ends of the cardines" of the maxilla.
    Now, when the labium is retracted by means of muscles attached to
    the mentum, the submentum turns in the loral socket and a-.-unes a
    position at right angles to the mentum while the lorum itself turns
    somewhat on its articulations with the cardines. This great freedom
    of motion is permitted by the loose membrane of the fossa in which
    both the maxillae and the labium a re suspended.
    The observer, however, can not fail to note that beside this motion
    of the entiq'e labium the tongue itself, or gloss-a (Gls), performs a
    conspicuous independent movement of its own. It is by far the most
    active member of the mouth parts during feeding, being actively
    thrust out and retracted while its tip is constantly moved about in
    a way suggestive of its being delicately perceptive of taste or touch
    or perhaps to both of these senses. So great is the retractile power
    of the tongue that its tip, which normally extends far beyond the end
    segments of the labial palpi, can be drawn back entirely within the
    latter. This contractile activity appears at first sight to be due to
    elasticity, but a closer examination will show that the entire ligula,
    i. e., the paraglossue (Pgl) as well as the glossa (Cis), move.-, back
    and forth and that the action is due to a retraction of the base of the
    ligula (fig. 15 F, Lg) into the anterior end of the mentum (Jitr).
    The ligula is supported on a membranious cone at the end of the
    mentum whos-e walls are strengthened by three thin chitinous plates,
    two above (F, 1p) and one below (D, o). By the contraction of
    muscles situated within the mentum (fig. 16, 1RJ3cl) and inserted
    upon the base of the ligula the latter is pulled into the end of this
    cone whose walls, including the chitinous plates, simply turn inward.
    But the tongue does possess also a contractile power of its own by
    means of which it actually shortens its length. A flexible rod arisingl,
    from the median ventral supporting plate (fig. 15 D, o) of the ligula
    extends throughout its length. The base of this rod is curved down-

    ward and has two muscles attached to it. This is shown by figure
    15 H. where the rod (r) is torn fromln the glossa (GIs) basally so as
    to show the niu-cles (2RMcll) inserted upon it. and its connection
    with the plate (o). By the contraction of the muscles the rod bends
    at its base and is drawn back into the mentum. The glossa thus
    shlortens and becomes bushy just as does a squirrel's tail when one
    attenipt: to pull tlhe bone out of its base.
    The protrusion of the parts is due to the pressure of blood driven
    into the ligula from the mentum, while probably the glossa extends
    also by the straightening of its rod as the muscles relax. Wolff
    descril)ed a protractor muscle at the base of the ligula. The rod of
    tlhe tongue is certainly lnot in itself contractile, as supposed by
    Cheshire, who looked for evidence of muscular striation in it. It has
    mostly a transparent and cartilaginous appearance, but is presumably
    The mouth parts, their action in feeding, and the muscular mech-
    anism by which they are moved have been elaborately described
    and illustrated by Wolff (1875) in his mnonograph on the organs of
    smell in bees. Most unfortunately, however, Wolff's paper was
    written to show that the seat of tlhe sense of smell is in the mouth,
    a most errolneol.s notion, and the title of his paper based oa this
    notion has caused little attention to be paid to this work on the mouth
    parts of the bee. which is one of tlhe best anatomical treatises ever
    p)rodliuced on the mouth parts of any insect.
    It still remains for us to dlescril)e the detailss of the glossa and its
    particular fuinctiion in feeding. Tlihe tongue is not a solid appendage
    nor vet is it truly tubular. A compromise is effected by the longi-
    tudinal groove (fig. 15) A and D, k) on its ventral IIsurface which
    expands within the tongue into a large cavity occupying half of its
    interior (E. Lilm). The glossal rod (r). which has already been
    mentioned. lies in the dorsal wall of this channel and is, hence.
    really not an internal but ;in external structure. The rod is itself
    .,I',ove1 along its entire ventral length (EV. 1) and this groove again
    i-, converted into a tuilbe by two rows of short hairs which converge
    from its n:mrgins. "l'le lips 4f the ventral groove of tlhe glossa are
    so deeply infolded that its cavity is almost divided along the midline.
    Ihentce. the gl(s:sa might be described as containing three channels-
    a small median dorsal one (1) and two large latero-ventral ones
    Thel glossal rod (fig. 15 r) is very flexible but not contractile, as
    already sAted, 11cd. 1 I is mstly .leV r and catilaginous in appearance,
    i-, ventral groove (1) alolne 1beii"g lined by a deposit of dark chitin
    (fig. 15 C and E). Its slial, iin sect ion is sufficiently shown by the1
    figure,.s. Tli' w;ll. of tlhe l. e 4 rge e.lanels of the proboscis consist of
    a ldelicatc i eibrane (C ;amid E. ) covered with very small hairs.



    The entire ventral cavity (Liit) with the rod (r) can be ev:gigmatcd
    through the ventral cleft (Z') by blood pressuire from within. A
    Cheshire points out, this permits of the ch l;lels being (clealid in
    case of clogging by pollen or any foreign matter.
    It is supposed that these glossal tubes are of (,especial service to the
    bee by enabling it to take up the smallest drops, of iect,'r--quantities
    that would be lost in the clumsy tube formed between the parts of
    the labium and the imaxilla'. The suction miust be in large part
    capillary attraction, but here again the shortening of tlhe glossa by
    the retraction of its rod must squeeze the contained nectar out of the
    upper ends of the channels where it is received upon the ventral flaps
    of the paraglosso (fig. 15 F, Pgl), from which it runs around the
    base of the tongue (GIs) within the paraglossao to the dorsal side of
    the mentium (.lit) and so on to the mouth.
    The maxillae and labium of both the queen and the drone (fig. 11
    B) are smaller and weaker than those of the worker, and neither of
    these two forms is capable of feeding itself to any extent. If a
    hungry queen be given some honey she attempts to eat it and does
    imbibe a small quantity, but at the same time she gets it very much
    smeared over her head and thorax.
    The mouth is hard to define in insects; practically it is the space
    surrounded by the bases of the mouth parts, but strictly speaking it
    is the anterior opening of the alimentary canal situated behind the
    bases of the mouth parts (fig. 19, Mlth). Yet the enlargement, of the
    alimentary canal (Phy) immediately following this opening is never
    spoken of as the mouth cavity but is called the pharynx. On the
    other hand the so-called epipharynx (Ephy) and hypopharynx
    (absent in the bee) are located in front of this opening and are con-
    sequently not in the pharynx at all, the former being attached to the
    under surface of the labrum and clypeus, while the latter is -ituated
    on the upper surface of the base of the labium. These and numerous
    other inconsistencies in the nomenclature of insect morphology have
    to be endured because the parts were originally named for descrip-
    tive purposes by entomologists who were not familiar with scientific
    anatomy. In this paper the term mouth will be applied to the true
    oral opening (fig. 19, IMth). The space in front of it between the
    bases of the mouth parts may be called the pl'eoral cavity.
    The duct of the salivary glands of insects in general opens upon the
    base of the labium in front of the hypopharynx. In the honey bee
    the salivary opening is on the dorsal side of the base of the ligula
    between the paraglossoe (fig. 15 F, Sal)O). This alone would show
    that the glossa is not the hypopharynx of the bee, as many authors
    have supposed, for otherwise the opening of the salivary duct should
    be ventrad to the base of the glossa. In fact, this makes it clear that

    22181-No. 18-10-----4


    tile bee does not po!-e.- a lAhypopharynx. There is. however, a con-
    .spicuouL chitinous plate located on the anterior part of the floor of the
    pharynx (fig. 10) s) having two terminal points hanging downward
    over tlhe lower lip of the oral aperture, but, although this plate is truly
    hypopharyngeal in position, it is not the homologue of the organ
    called the hypopharynx in other insects. It is variously developed
    in all IHyNmeitoptera. being simply a chitinization of the floor of the
    plharynx, and should be called the plJu-yn/yeal plate (SelIlundbein of
    Wolff). It will be more fully described in connection with the ali-
    meiintary canal. If a hypol)lpharynx were present it should be situated
    on the upper side of the labium (see fig. 3 D, TIphy) but there is here
    prets'elt only a plain arched membraniious surface in thle honey bee
    and other typl)ical IIymenilopl)tera.
    The external location of the salivary o()pelinIg enla)les tlhe saliva
    to be mixed with the food before the latter enter-i the mouth. Tillis
    is iiecessary in insects since the jaws are also onl tlhe outside of the
    SaIDO T
    ', Lg TMcl
    ci /;'SaID
    GsPgl, -6 ^

    r-- ---1RMdl

    Lum 1 n
    t Mt
    I'Pj,;. 16.-Mediain section thiirough dist:il1 half of mentum (MJU) and base of ligula (Ly)
    of worker, showing oipedini ,t salivary duct (N',IIWO), and uniuscle.s c' not't'd with
    Iigil; iia and the "salivary syrin g," (t).
    lnouth, and whliatever chewing or criishing the food receives from
    tlium is colse(quently d(lone in the preoral cavity.
    In some ii-ects the saliva i- w-ed for other purposes than diges-
    tioli. For example, the saliva of omlle predaceous ilisects with pierc-
    ing mouth part, beloigi,,g, to the order Hemip)tera is p)oisonouis, and
    wheii (me of the-se insects bites." the saliva is injected into the
    woiund by a ,special pump. Tlie bite of tlhe mosquito is made painful
    likewise by an irritant S''cretioll fromn a part of the salivary glatiids.
    Bee-, appear to haive the power of letting their saliva run down tle
    tongue vliel nIec(*essa Wry to dissolve a hard subl)stane like sugar and
    reidtIr it capa le, of being takevn up in solution, for they do not eat
    sulgar witli t(h'ir mandille.s. Moreover, tllhere is evenll a sort of pump
    or so-cialled -.livarv i "vriige at tlhe termiiiHation of the salivary
    duct in tll ligiila. by vieanis of which tlhie secretion can be forcibly
    (jc.t(e(d fiomi thlie openinlIg.
    TIw -alivary opening o' t, e base of the llgiila (fig. 1 F, SalDO)
    leai- intoi ;I deep t'i-a -'v'.e p it with collapsiblle cartilage-like walls
    havig its, deepest pal't turned hlorizontally toward the base of the



    labium (fig. 16, t). The salivary duict (SalD) bends dowuwardl in
    the anterior part of the mentiiim (.it) and opens into lthe posterior
    end of the pit (t). When the retractor muscles (1R.11cl) of the
    liguila pull the latter back into the mentum the lips of the salivary
    pit must neces.-,arily be closed. The simulfta eo)us (cltraction of the
    elevator muscle (u) attached to the roof of the horizontal part of the
    pit must expand the latter and .-ick the saliva from the :alivary duct.
    When, finally, these muscle- relax and the liguila is driven out by'
    blood pressure in the mentum, prol)ally produced in part by the
    contraction of its dorsal transverse muscles (TMcl), tlhe saliva in
    the temporarily formed bulb must b)e squirted out upon the base of
    the tongue. Wolff (1875) calls each dorsal longitudinal muscle of
    the mentum (1RMcl)-the two inserted upon the b:aal hooks (n) of
    the glossa (fig. 15 H and fig. 16)-the retracwtor lingua( longus. The
    large ventral retractor muscle of each side (JRMcl) he calls the
    retractor l1tijg. biceps since its anterior end divides into two parts,
    one of which is inserted by a tendonous prolongation upon the bas'e
    of the glossal rod (fig. 15 H and fig.16, r) and the other upon the
    base of the ligula. The use of the word lingua in the-c names is
    objectionable because, as already explained (page 45), the lingua is
    properly the true tongue or hypopharynx. Ligula should be ,ub-
    stituted for lingua." The dilator muscle (fig. 16, u) of the salivary
    pit (t) is termed the protractor linguwe by Wolff because, as he sup-
    poses, when the ligula is pulled back into the mentum the position
    of this muscle is reversed, so that a contraction of its fibers would
    help to evert the ligula.
    The glands that furnish the saliva lie within the head and the
    thorax and will be described later in connection with the alimentary
    canal and the process of digestion.

    Ephy Lm
    \/ ------ L r

    -: "o o'- .* .' : "__. "*' 't i
    ':: """" :'"Ephy
    A B
    FIG. 17.-I'Epiplhrynx (Ephi/) and labrum (Lm) of worker: A. ventral view; B,
    anterior view.
    The epipharynx of insects in general may be described as a dorsal
    tongue, it being a median lobe developed on the roof of the preoral
    cavity from the dnder surface of the clypeus or labrum and situated
    opposite the hypopharynx.


    The epipharynx of the bee is a large three-lobed appendage de-
    pending from the roof of the preoral cavity just in front of the mouth
    (fig. 19, Ephy). Seen from below it is triangular (fig. 17 A) with
    the apex forward. Its median lobe has the form of a
    '^ high, vertical, keel-like plate, while the lateral lobes
    Sf y aic rounded but have prominent, elevated edges con-
    J verging toward the front of the keel. The appearance
    in anterior view is shown 1)y figure 17 B. Situated
    r-.1., IS ense on the posterior parts of the lateral lobes are a num-
    01 1- Ia u iwob-
    n'ily of taste, her of sense organs, each consisting of a small cone
    f r omI ep with a pit in the summit bearing a small hair (fig. 18).
    These are regarded as organs of taste.
    Wolff (1875) made a most thorough study of the epipharynx,
    which he called the "palate sail" (Gaunmensegel) on account of the
    high median crest. His drawing is the standard illustration of the
    organ found in nearly all books on the anatomy of the honey bee



    L" 'w"V -LbPrp
    1"1'. 19. MIvdi;i 1,ingil udimiil section tf hiiil of worker, but with entire labium atttch,'d(1,
    ,'fiwilg inii(rn;il iorg:ns (Xriept musiicles ind brain.

    ;id1(1 in rmost works on gTlleraI inlsec(t aliatomVy and thie selse organs.
    \Volff, however, regarded the sensory co()nJes as having an olfactory
    f1unctiIon. :Illd tlis led liill to erronoius co()nclusions regarding tihe
    fIll'io 111: of (J vhr:Il ( iler ''rg iis. For exaip)le, lie thought that
    t4l, iiri dibliilhr glinad, p;oured a liqttid uipon tlhe surface of the



    epipharynx which kept it moist and
    particles, while he ex- Ant
    plained the inhalation
    of the latter into the
    preoral cavity as
    brought about through i
    the contraction of the
    air sacs situated about Ten.--
    the mouth. Wolff's Eps,.
    anatomical researches
    are without doubt Tra
    some of the best ever
    made on the bee, and
    it is due to his mis- 8
    taken idea of the loca-
    tion of the sense of
    smell, which, as al-
    ready explained, is on
    the antenna, that we
    have received from
    him a most excellent ..
    account and detailed
    drawings not only of
    the epipharynx but of
    the mandibular glands,
    the mouth parts, the
    salivary pump," and
    the respiratory organs.




    The apparent thorax
    of the bee (fig. 20,
    T.-IT, and fig. 21)
    and of most other
    Hymenoptera is not
    exactly the equivalent
    of the thorax in other
    insects. The middle
    division of the body,
    so conspicuous in this
    order, consists not only

    calpabl)le of absorbing odor

    11 le


    FIG. 20.-Dorsal view of ventral walls and internal skele-
    ton of body of worker.

    of the three leg-bearing segments, which alone



    constitute the thorax of all other insects, but also of the first ab-
    doninal segment. The conspicuous necklike constriction posterior to
    the ba-e of the hind legs (fig. 21, Pd) is, therefore, between the first
    and the second abdominal segments (fig. 1, IT and lIT).
    The thorax of the honey bee at first sight looks entirely different
    in structure from that of all other insects except related Hymenoptera,
    inll tl higher families of which group it is more highly modified than
    in any other order of the whole series of insects. When, however, we
    examine the thorax of one of the lowest members of the Hymenop-
    tera. such as a sawflvy, we are surprised to find that, in each segment,
    the structure agrees very closely with our ideal diagram of a general-
    ized thoracic
    T2 segment (fig. 4).
    r-,--- A2, The three seg-
    TSc12 r ments are per-
    l.1 .W r) pfectly distinct,
    .-and the first
    Sct2e /. P3 abdominal seg-
    p t T Tment, while it
    ,in> 1 )may be clearly
    separated from
    -Pd the rest of the
    (1 _p abdomen, is not
    kf fused into the
    eM ofti ,.-to .e( ithiorax so as to
    appear to be a
    tota t part of it. If
    P5 If,.
    Cx, 5 now, we exam-
    dl inee representa-
    tives of several
    I.',. 21.-Thorax of worker, left, side, with intersegmental lines
    -,,nwh;I( t exiggerali',l. .-I(,i% lg iuzi,'h r.'' x (TI7, Ep,,t,. ('.', fam ilies inter-
    IjII'Nlthorlax (T,, sji.s.. l s., wi.. metathorax (T3:, P1::. mediate between
    Id.. ('') and pirop,,iieum or first alld,,niiAl .segment (17T .
    the sawNiflies and
    the I ees. the line of specializati(ii that lhas produced the bee thorax
    1,. 'oIi-,. perfectly evideint. The iprincipl features in these miodifi-
    I,.liozis are the following:
    (1) TI1i lateral and ven t ral parts of the prothorax ( figs. 20 and 21,
    Eii. and S,) are suspended loosely in a large membranous area
    which is continuous anterior)] N as the neck. They thus form a sort
    of -itpei).isoriizin for the frionit legs. whicli appears detached from the of tlhe thorax. (2) Jlle plotelrg'u, (T,) is solidly attached to
    th,( a lit(Teor edge of the i)iesothoorax and its lateral parts extend
    dw viiwvard till they meet oii the venter heldind the prosternum (figs.
    6.() ,ad 21). ( T1) 11w 1p(pstliitiiii (postscutellim) of the inesothorax
    (fil..-2. I'P.; 23 A. PV.I) is entirely ifvLirlnate(l_ into the cavity of
    tihe lio ax and is reduced to the form of two lateral arms of the large


    THIlE T110RAX ANI) I'TS Al'PI'ENI)A<;I..S.

    internal postphragiiia, (Pph) which la,- no ilmediani tergal collction
    ait all. (4) The ieitatergui (figs. Jl alnd 2' A, 'T,:) C('-is" of a
    single ii;iarrow plate. (5) lThe minetafpletriiii (fig. 21, Pl, and /,":)
    shows )no trace of a 4livision into ep)iteri11um1 and ('piii(rIiij. liut is
    divided into an upper (P7,) and a lower (/d,) pleural plate. (6)
    File first abdoiniiital ti'erguim (fig. 21, IT) is solidly attachlled to the
    met athorax aiid forms an intimate part of the tlhoracic mas.
    We :lshall now proceed with a more detailed acmi it of tlhe thorax.
    and the reader should occasionally turn back to figIre 4 (p. 19) in
    order to keep clearly in mind the parts that imilake iup a gecenralize(l
    thoracic senieiient.
    The park of the prothorax are so, >ep rated from each other that
    Ihey -app,-,r to belong to different s"gmenLts. The p)rotergiin (fig. 21.
    T1) foriii a collar completely encircling the front of the ieso)thorax.
    On each side a large lobe (Or) projects p4)-teriorly as f;ar as the base
    of the front wing and coit-titutes a protective shield over the first
    thoracic spiracle. The terguinm presents a median r ve.e groove,
    -iner "4ro pat wich parts itay
    d(lividing it into an anterior and a po.terio part, which parts ay
    be called the sciitumii (fig. 23 A, T1, S,/) and -cutellun (Sel). The
    1)propleulrIlU (figs. 20, 21, Ep.,l) consists of a:i large plate presenting
    both a lateral surface (fig. 21) and a ventral surface (fig. 20). On
    account of the position of the coxal articulation (fig. 21) this plate
    would seen to be the anterior pleutral plate alone (see fig. 4), which
    is the episternum. In some Hynieioptera the epimerumni is repre-
    sented by a very small plate on the rear edge of the episterniiin.
    The anterior ends of the two epi.-terna form knol)s which loosely
    articulate with the occipital region of the head (figs. 11 B, 20, and
    21). Lying just ventrad of .eachl is a -lendler cervical sclerite (fig. 21,
    di). The prosterniin (S,) is shown by figure 20. It carries a large
    entosternumin (Fo,), forming a bridge over the nervous sVyteni 6e1)hind
    thle prothonracic ga nglion (fig. 52).
    ThIe mesotergum, a- -een in its naturnal j)-itioii (fig. 21, T,), coil-ists
    of a large anterior scutiuml (Set.,) and of a :sialler but very prominent
    posterior scutellum (Sd2), separated by a very distinct suture (r).
    The scutellum lias two latero-ant(erior areas partially separated from
    tlie median area by sutures. When tlie mesotergum is detached fronl
    the rest of the thorax (fig. 22) it is di-covvtred that there is attached
    laterally to the .scitellum a large pos-terior internal] part, which doe.-,
    not show on tlhe surface at all. This is the representative of the
    postscutellum (P.-7) and its phragna (Pph) constituting the post-
    notutim (P-) of outir ldiagramnimatic -egmient (fig. 4). The proof of
    this, again, is to be derived-from a study of the lower Hymenopteran
    families. In some of the horntails (Siricidve) the pos.tnotuni or
    postscitellum is a prominent plate on the surface of the dorsumi be-
    hind the scutellum. In S;r/'. (Siricidue) this plate is sunken below



    the general surface and mo:tlv concealed between the mesothorax
    ald tl' metatholrax. In higher families such as the Pompilide the
    p -(t i,,tum of til' llie,-,tergumn is entirely concealed by invagination,
    but it still carries a very large phragma. When, now, we come to
    the h1ighe-t imenlbers of the order we find that the median part of the
    postnotili ill tlhe Inesothorax is gone entirely and that it is repre-
    eente l only by tlhe lateral arms (figs. 22, PY; 23 A, P.1%) carrying
    the large, purely internal postphragma (Pp)h).
    Tie mesopleurum i- large anmd consists principally of the episternum
    (fig. 21, Jp.s:), whiich, however, is continuously fused with the meso-
    sternum (figs. 20 and 21, S8). The pleural suture (fig. 21, PS.') is
    short and :inuoius anld does not reach more than half way from the
    wing proce-s to the )baset of the middle leg. The epimerumn is reduced
    to a -iiiall double plate lying above the episternumn and posterior to
    the wing proce-,s (figs. 21, Epmn and 24 A. Ej))m and Epm). The
    pleural ridge (fig. 24 B, PR)
    N is weak. but the wing process
    SSc i (1P') is well braced by a num-
    "-'^^ :U be tr of accessory internal ridges.
    Sct'/^ ^ One preparapterum (2P) and
    .^PN ^ one postlparap)terumn (JP) are
    ....../" -.^ 1)resent. Lying behind the
    ), po-tparapterln is another
    po-pal -1111 i" allother
    pn ." larger sclerite (fig. 24 A and
    PNP POph" B.1 p,), who-e anterior elld is
    its. 22.-Lateral view of i,,-,otr.,',,u of articulatedd to the edge of the
    worker, removed triiii the rest of thorax to
    show ;ir;e internal ,i,-i-'tellium (post- epimerum in and whose posterior
    niittim. P'.v) iandi ii- i, r:iti,.i l'jih) not taperino" end is loosely asso-
    vi-illi normally in the bee from exterior. e i i
    'iate(d wvithl the termlinal arms
    of the po-totim un (fig. 22, PY. :mi d pi). This sclerite might be
    iregfi rd] ai- the frIrtm Ii p:tiripteruiil. 1kiit it is muiicli more probably
    tilt rI.pIvi'i-0itative of n -iil i t1ciin;i 1' 1ha r of the postnotulml present in
    otier I iTyieviiopcrir, suc li as P px'';, which connects this tergal plate
    with flite epimeriii. thollugh in tis genus it is not detached from the
    m: ii p(,-tnola:l -cleritc.
    INitth (1i mesosternum (fig. 2 ,) an(ld t1ie metasternum (S.,) con-
    ril mite to tlie forimitit I of :, lal're entostvrium un ,+:), which forms
    p li'otc.tiit,- i1rid'i1 over tlie ct.,n iiiil mi ,i( tl(dioracic and lietathoracic
    gaigflini (lig. 52) ;aid affords atnacliin'iit for tlie ventral longitudinal
    mi,.i-1cs of the thorIx (fig. -71, h1,e/).
    'I'l(. metathorax of n very narrow .-eries of plates (fig. 21,
    '., I'!, ali(d 1,1) ct1rt,-etid Iet'ween'i lite inmesotliorax and the first
    : idoii],, iii l t,'mii (I I siI, 'k 1l.'l is a singllt. nal ow, transverse
    -,ljilt (-1'-. "'1 :1idl A'.'.\ T,,) wiliiing Oil titie sid(les, where it carries
    tli. \\ig. 1iy)i twi o wiing lirioCs.'s (fig. 23 A, .IAY' and P.VP'). The



    ordinary tergal d(ivi'-ionw s, ,hi to be entirely olirtedl. The meta-
    p1lerium coii.i-4t of ;i dor-al plate (fr. 2- 1, PI:) jiippotilltr tile hilld(
    wing and of ai ventral plate (pl:) *,arryi n tlie 1iiid legr. Tlic iee two
    functions ccrtaiIlly identify tht-e two plate- a;s co-sti iti nP together
    the nuetapleurum, 1,ht there i. al .olutely no tr.,ce of a division into an
    episterlilini and ani epinierumi. Once more. therefore, we have to g:o
    back to the generalized Hymenoptera to find out what lhal- happened.
    N fstct




    FIG. 23.-A, thoracic terga of worker separate froin one another, shoiwin- pritergumn
    (TI), mesotergum (To) and its internal )postscutellum ([,,- ,itumr PN2) and plira-ima
    ('ph.i2), metaterumin (Ta) ind( propodeum or first abdominal t.r.:tlm (IT); 1, ventral
    view of principal or notal plate of me-uterguim.
    The answer is simple. Sre.,e has a typical metaplerumii consisting of
    an epistermi and( epinIIerlin h-eparated by a complete pleural suture.
    In the higher forms thi-, suttuire simply disappears, and consequently
    the pleuirunti shows no traces of it- original component plates. The
    division into a wing-)earing and a leg-bearing plate iQ. therefore, a
    purely secondary one.
    None of the Hymenoptera hlias s-eparate troclhantinal sclerites (see
    fig. 4, Tn), but, since the coxw are articulated ventrally to knobs



    (fig-. "20 and 21, .) apparently belonging to the sterna, it might be
    .-.llppo-edl that the trocllantins have fused with the latter plates.
    The posterior part of the thoracic mass (fig. 21) consists of the
    first abdominal tergum (IT), which fits into the deeply concave pos-
    terior edges of the minetathorax and forms the peduncle (Pd) that
    c.arrie- tlhe re-t of the abdomen (fig. 32). It consists of a single large,
    -tronly convex .clerite (figs. 21 and 23 A, IT) bearing the first
    abdominal spir:cles laterally (ISp) and having its surface divided
    into (-veral areas by incomplete sutures.
    ay entomologists find it difficult to believe that this plate, which
    Mo apparently belong. to the thorax, is really derived from the abdo-
    men. But tlhe proof is forthcoming from a number of sources. In
    the first place, the thorax is complete without it and the abdomen is
    incomplete without it, the latter having otherwise only nine seg-
    mlients. Agailln, if the plate is reckoned as a part of the thorax we

    WP2 wP
    2P 3P pn pn. P R\ 1 -2P

    !, Fpm Epm.


    A B
    Fit,. 24.-A. uipp'r part tif left mi-q.opleiirnm of wnrkor, external; R. inner view of same.
    should have the a-nomaly of a thorlax with three pairs of spiracles-
    thlere 1eing the mono1:al two on each side situated, as they always are,
    Between the true t1ioracic" segrinents. lFurthermnore, comparative anat-
    omy shows us tliat in somie of tlhe sawflies (Tcnthredinidw) tlhe first
    abdo)mial ti1rauni, while sepairaited by a wide inembranous space
    from tlhe -e'void. is. not at all incorporated into the thorax. In a horn-
    tail -11c' as S.i,., (Siricidaw) thle entire first al)dominal segment is
    ft'-ed to the po(sterior edge of thle mietathorlax and is only loosely
    joined to tli' next aldomIial segment I) inembrane. This insect
    affolrd. tlilre fol'e, a m,110t complete demonstration of the transference
    of thii- -,iaii 'jt froimi the rest of tlie abtdomIen to the thorax. Finally,
    we l,;v' d alb-olut.e i)ro(of of its albdominal origin based on a knowledge
    of develop)IIent, ft'r it l]Ias 6C1 ),t soliV'n bIy Packard from a study of the
    b1)111iill.ic, thlat tlh' first abdomi inal segment of thle larva is trans-
    It'rredl during tihe pupal meittam orphlosis to the thorax and forms the



    part under di,.cu.,,-ioji. We ,henIce .-ee that not only the lirst abdoii-
    nal tergiim but the entire -,egmineit has undergone tr;in.,,po.ition,
    though the veintral part hlas disappeared in all the higher famiilies.
    This transferred part has been named both the ind;lin .NCgu1',,t and
    the propodeum by writers who recognize it as belonging to the abdo-
    men and not to the thorax.
    The names current among systematists for tlhe back plates, of
    Hymenoptera afford an excellent example of the error, that ento-
    mologists may be led into through an ignorance of the comparative
    anatomy of insects. They recognize the protergum as such and then,
    knowing that there are yet two segments to be accounted for, they
    call the mnesoscutltum the mesonotum," the mesoscutellnm the
    "scutellum," the metatergum the postscutellum (being unaware
    that the true postscutellum is deeply concealed within the thorax),
    while the. first abdominal tergum is called the metathorax. Such
    a nomenclature assigns both pairs of wings to the mesothorax. Too
    many systematists working in only one order of insects do not care
    whether their names are applied with anatomical consistency or not.


    In the study of insects the wings always form a most interesting
    subject because by them insects are endowed with that most coveted
    function-the power of flight. It has already been stated that the
    wings are not primary embryonic appendages, but are secondary out-
    growths of the body wall from the second and third thoracic seg-
    ments. Therefore it is mo-t probable that the early progenitors of
    insects were wingless, yet for millions of years back in geological time
    they have possessed these organs in a pretty well developed condition.
    Nearly all of the insect orders have some characteristic modifica-
    tion of the wing-veins and their branches. None of them. however,
    departs nearly so far from the normal type as do the Hymenoptera,
    even the lowest members -of this group possessing a highly specialized
    venation. Before beginning a study of the Hymenopteran series
    which leads up to .the bee the student should first turn back to figure
    6 (p. 22) and again familiarize hiimself with the generalized condi-
    tion of the veins and the articular elements of the wing. By com-
    paring, now, with this diagram the basal parts of the wing of a
    sawfly (Itycorsia discolor, fig. 26 A) it will be easy to identify the
    parts of the latter. Vein C has two little nodules (C, C) cut off from
    its basal end which lie free in the axillary membrane. Vein Sc articu-
    lates by an enlarged and contorted base (Sc) with the first axillary
    (lAxe), while vein R is continuous with the second (2Ax). The next
    two veins that come to the base and unite with each other are appalr-
    ently not the media and cubitus but the first and third anals (1A and



    3A), since they are associated with the third axillary (3Ax). In this
    species s the subcosta (Sc) is entirely normal, but in the related horntail
    (Sireax flavicornis, fig. 26 B) the enlarged basal part of the subcosta is
    almost separated from the shaft of the vein, while the latter (fig. 25A,
    So) is short and weak. A study of the venation of this wing leads
    us to believe that the vein which arises from the radius a short dis-
    tance from its base is the cubitus (Cu). Therefore the basal part


    F';. 25.-Wings of Hymenoptera and their b:s.l articulair sclerites (lAx-4A.r) : A, Siraer
    fluric'orni8, front wilng; B, Pi(psi. sp., front wing; C, honey bee, front wing; D, honey
    bee, hind wing.
    of the media is either gone or is fused with tlhe radius. Since we dis-
    o*ver its branches in the distal field of tlie wing, arising from the
    trunk of the radius, we conclude that the latter is the case. By this
    sort of reasoning we may arri'ie ait the Comnstock and Needham inter-
    pretttion of the wing illustrated at .l, fig. 25. From this it is evident
    That thle branches of both tlhe radius and( the media have been bent
    bacl toward the posterior margin of tlhe wing.



    -AxM F

    -~ R-t-M

    LAx -.J


    2AX -



    FIG. 26.-Basal elements of wings of Hymenoptora: A, hast of front wing of a sawfly
    (Itycorsia discolor) showing comparatively generalized iirrnwn-nient ,f veins and
    axillaries; B, bases of anterior veins of front wing of a hornteil ISirex flavicornis),
    showing detachment of base of subcostal vein (8c) from its shaft; C, crorrlesponding
    view of anterior veins in front wing of a tarantula-killer (Pepsis sp.), showing com-
    plete absence of shaft of suhlcosta. but presence of basal part (Sc) fused with base of
    radius (R) ; D, axillaries of anterior wing of honey bee worker; E. te-ula of worker;
    F, base of anterior wing of worker showing absence of shaft of qutiiosta but presence
    of scale (Sc) derived from its base; G, axillaries of hind win--, of worker, the fourth ab-
    sent in bee; H, base of hind wing of worker, showing absence of costal and subcostal veins
    and fusion of bases of subcosta (S'c) and radius (R) into large humeral mass; I, attach-
    niment of front wing to scutum (Sct..) and scutellum (cl.,) of mesotergum ; J, under view
    of E-nd of mesoscutellum (SclC) showing attachment of both first (lAx) and fourth
    axillarivs (4Ax) to posterior wing process (PNP), an unusual connection for first axillary.








    Taking this wing of Sirh'ex as a foundation let us proceed a little
    higher aid examine the wing of a Pompilid, such as Pepsis (figs.
    _2" C and 2r_ B). We observed that in Srexr (fig. 26 B) the basal
    part of vein Sc is almost separated from the distal shaft. In Pepsis
    (fig. 211 C) it is entirely a separate 1)piece, to which is fused also the
    1)ase of vein R. Moreover, the shaft of Sc has disappeared entirely
    (fig. 25, B). Thus there is at the humeral angle of the wing a large
    ci.itinous mss (fig. 26 C, Sc and -R) representing the fused bases
    of both the sub.cota and the radius, which is associated with
    both the first axillary (lAx) and the second axillary (2Ax).
    If now we proceed to a study of the front wing of the bee we
    find that its basal characters (fig. 26 F) are more similar to those of
    8;,..,' (B), while its venation (fig. 25 C) resembles more closely that
    of Ppxi. (B). The siubcostal scale at its base (fig. 26 F, Sc) is
    Hot fuised with the base of the radius, but the dlistal part of the
    siib-)costa is gone (fig. 25 C), as in Pepsis. In the hind wing of the
    bee (fig. 26 H) the bases of the subcosta and radius are fused into
    one large humeral mass articumlating with tlie first two axillaries
    (lAx and 2. l.e). The third axillary (3.1,') is well developed but
    the fourth is absent. The venation (fig. 25 D) is reduced to a very
    simple condition, but to one just the opposite from primitive.
    The details of the axillaries in the two will)ngs, are 1)1ow ly figure
    i; D and G. The fourth (4Ax) is, well developed in the front wing
    (D) and lhas a lIarge accessory sclerite (y) connected with it, upon
    which is inserted a long slender mus-cle (fig. 28, cc). A very small
    accessory sclerite (ax) occurs clh)se to tihe muscle plate of the third
    axillary (3Ax). The-e are called accessory sclerites l)ecause
    they are of irregular occurrence in the wing bases of insects generally
    an(d are developed in coniniection with the muscle attachments. Simi-
    ;Li olines occur in the hind wing ((G, t.') ill connection with the
    s,,econd (2Ax) and lhird axillaries (3.1,.).
    Tlie froit wiN-" is att ached to tlhe posterior half of the side of
    the me-onotum. The anterior notal wing process is bilobed (figs.
    22, 23 A, T.,, .IVP) and is carried by tihe scitumn. while tlie p)os-
    terior process (PP) is carried by the scutellunm and is mostly
    hidden beneiatlh the anterior wing process. The two wing processes,
    in fact, are so close together that the first axillary articidulates not
    oly with the first but also with the second (fig. 26 J). The axillary
    'ordI (fig". :; F, .1.,'1 ) a iri ",' froi, a lobe( of tlie sciitellul, over'ilallpedl
    b)y tle literal margin (I and J, AxC). In the hind wing, where tlhe
    folurili ;ixill;vry i, ;.ise.t, t th third articulates directly with tlie
    p,(,stVerior ,ot il wing process of lie nietalergumn (fig. 23 A, 7;:, P I.P).
    Tie I;,s of le f ,' ,ro ent wig i overla))pped by a large scale (fig. 26,
    L1 and I, T1) called the t(giiia. It is carried by tlie axillary mnem-



    brane, to which it is attached between the humneral angle of the wing
    base and the edge of the notumi. The tegiln- are presenIt in most in-
    sects, generally on the )base of each wing, but they usually have tlhe
    form of small inconspi ious hairy pads, as shown in the diagramll
    (fig. (1, Ty). In the flies, moths, butterflies, and Ilymenoptera,
    however the tegulaw of the front wilgs develop into large consp)icii-
    o0lS scales-, overlapping the humeral angles of the base,, of tlhee.
    The motion of the wing in flight conIsists of both aIn up-and-down
    movement and a forward-and-backward moveietnt, which two conl-
    bined cause the tip of the wing to describe a figure,-eight course if
    the insect is held stationary. Corresponding with the-ee four move-
    mnents are four sets of muscles. In the dragonflies nearly all of the
    wing muscles are inserted directly upon the base of the wing itself,
    but in other insects, excepting possil)ly the mayflies, the principal
    muscles are inserted upon the thoracic walls and move the wing
    secondarily. In the lower insects, such as the grasshoppers, crickets,
    stoneflies, net-winged flies, etc., the two wing-bearing segments are
    about equal in their development and each is provided with a full
    equipment of muscles. In these insects the wings work together by
    coordination of their muscles, although each pair constitutes a sepa-
    rate nmechanismn. In such insects, however, as the true flies and the
    wasps and bees the metathorax, as we have seen in the .case of the
    bee, is greatly reduced, and what is left of it is solidly attached to
    the mesothorax. In the flies the hind wings are reduced to a pair
    of knobbed stalks having no function as organs of flight, while in
    the bees the hind wings, which are very small, are attached to the
    front wings by a series of booklets on their anterior margins (fig.
    25 D, Hk) which grasp a posterior marginal thickening of the
    front wings. Moreover, when we examine the interior of the bee's
    thorax we find that the muscles of the metathorax are greatly
    reduced or partly obliterated and that the great mesothoracic mus-
    cles serve for the movement of both wings, thus assuring a perfect
    synchrony in their action. Hence, it is clear that the union and
    consolidation of the thoracic segments in the higher insects is for
    the purpose of unifying the action of the wings.
    The muscles of flight in the bee may be very easily studied by cutting
    the thorax of a drone into lateral halves. The cavity of the thorax
    is occupied almost entirely by three great masses of muscle.. One
    of these is longitudinal, median, and dorsal (fig. 27, LMcl2)), extend-
    ing from the mesoscuitum (Sct.) and the small prephragma (Aph)
    to the large mesothoracic postphragma (Pph2). A small set of
    muscles (LMcl) then connects the posterior surface of this phragma
    with the lower edge of the propodeum (IT). On each side of the



    anterior end of this great longitudinal muscle is a thick mass of
    dorso-ventral fibers (TIl/cl) extending from the lateral areas of the
    nesosciitutn (St,) to the lateral parts of the mesosternum (S.). A
    contraction of the vertical muscles must depress the tergal parts,
    at the same time expanding the entire thorax inl a longitudinal direc-
    tion and -tretcling the longitudinal muscles. A contraction, then,
    of the latter muscles (LMJfcld) restores the shape of the thorax and
    elevates the tergal parts. Remembering, now, that the wings are
    supported frombe-
    LM2 low upon the
    FCt 2 pleural wing proc-
    \ t,.SCl2 esses and that each
    ; s is hinged to the
    XX back bly the notal
    X (.Twing f processes, it
    i rlear that a de-
    .IT pressiofl of the
    Aph dor;um of the
    ta -Pphs thorax must ele-
    _V___c p vate the wings and
    tMclves. 'LMcI that an elevation
    tudnaof the dorsum de-
    Bt presses them-the
    A o ppleural wing proc-
    s, esses acting as the
    ,"3 CX t
    VMCl z Cx,2 fulcra. Hence, the
    Flo. 27.-Median section through thorax of drone, showing chief up-and-down
    longitudinal miinvles (L.]1C12) of mesothorax going fromi scutum (.`ct_,) and small anterior phragmi movemlents of the
    (.-ph)i to posterior plihrS ma (tdph.) of internal postscuitel- wings are pro-
    luhe (postnontum) of same segment, also showing vertical
    miesothora'ic muscles (Vlncl), ind ventral longitndinl muss- duced by these
    cles (Iin), aind longitudinal muscles of metathornx great thoracicnmus-
    (L.fcIl.) going from postphIirgma of mesothorax (i'ph..) to o
    posterior edge of propodemn or first : lhdominll tergum (I7'j. 'les acting upon
    By alternate contraction of dor-'il longitudinal niizszcles and the shape of the
    vertical niuscles. roof of thorax is elevated and depressed.
    c.i;sing wings to beat (lownward ;ind upward respectively, thorax as a whole
    heing supported on fulcra f,,rnied by pletiIvl wing lrocesses and not directly
    (fig. 2.4, 1"12) of side walls of thorax. upon the wings

    thei.,,elves. The vertical muscles are the elei'atois and( the longi-
    tli(linal the dcl so,'rs.
    But besides, being iiioved up and down the wings can also, as l)efore
    tfitC-i, lbe ,xtei(ld('l aiid flexed, i. e.. turned forward and I)backward in
    horizontal plane 111)Ol the pleural wing process. The muscles
    wlIicl' UCCoIblslic] these movements lie against the inner face of the
    plei1,1zrii (fig. 28,s), and (':]v'l wilg is provided with a separate set.
    T'live etvwr mnile (P.l(lc) is til. iios( ailterior alld is iJnsertedl by
    ;. lon]g I1(.k Ul)1 tlhe preparapterlnii (2P). The latter is closely


    connected with the anterior part of the base of the wing so that a,
    contraction of the muscle turns the wing forward and at the saflo
    time depresses its anterior margin. For this reason the parapterinin
    and the extensor muscle have been called the projnttor aljpti-fOs,' aind
    the muscle is known also as the proinator m,.+fle. In -olne ins+ects
    which fold the wings back against the body this muscle is a great
    deal larger than ini the bee. The flexor mi.s Ic (RJMcl) consist of
    three parts situated upon the anterior half of the pleurum and in-
    serted upon the third axillary (3Ax) by long tendonlike necks.
    These muscles are antagonistic
    to the extensor and by their W&2 Ax 3Ax
    ** I .3P SA~t
    contraction pull the wing 2 ,
    back toward the body. Y,
    The mechanism which pro-
    duces the wing motion thus -
    seems to be a very simple one \ c
    and may be summarized as I_"
    follows: Each wing rests and V/1
    turns upon the wing process
    of the pleurum (figs. 24 and bb
    28, 1VP) by means of the
    pivotal sclerite or second axil- I'
    lary in its base (figs. 26 FAnd --lil -T
    28, 2Ax). It is hinged t the H 1
    back by the first and fourth
    axillaries (fig. 26 F, lAx and
    4Ax) which articiulae with
    the anterior and posterior FG. 28.-Internal view of right pleurum of
    notal wing procesSes (fig. 23 mesothorax of drone, showing muscles in-
    A A Pa d ) e serted upon parapteral plates (2P and 3P)
    A 27, 1 \P and PXP), re- and upon third axillary (.A.r). The win.,
    spectively. The large vertical rests upon wing process of pleurum (W'2)
    by second axillary (2Ax) ; it is turned for-
    muscles (fig. 27, VMcl) of ward and downward by the pronator muscle
    the thorax depress the ter- (PMcl), inserted upon anterior parapterum
    (2P) which is attached to costal head of
    gum, which pulls down with wing, and is turned back toward body by
    it the base of the wing and flexor muscle (RM1cl) inserted upon third
    hence elevates the distal part- axillary (3_1x).
    the fulcrum being the pleural wing process. The dorsal longitudinal
    muscle (LMcl) restores the shape of the thorax, elevates the tergum,
    and consequently depresses the wing. Extension and flexion of the
    wing are produced by special muscles (fig. 28, PMcl and RMcl) acting
    upon its base before and behind the pleural wing process. respectively.
    Besides these muscles there are several others (fig. 28) associated
    with the wing whose functions are less evident. Most conspicuous
    of these is a muscle occupying the posterior half of the mesopleurum
    (aa) and inserted upon the outer end of the scutellum. This may
    22181-No. 18-10-- 5



    be simply accessory to thle large vertical sterno-scutal muscle (fig. 27.
    V11cl). Another is a long slender muscle (bb) attached to the upper
    end of the me-ocoxa and inserted upon the postparapterum (3P).
    This is sometimes termed the co,'o-axillary mse. A third (cc) is
    inserted upon the tip of the accessory sclerite (y) of the fourth
    axillary and is attached to the lateral arm of the large entosternumin
    of the miesothorax and metathorax.
    3. THE LEGS.
    The legs of the honev bee are highly modified for several special
    purposes besides that of walking, but they are so well known and
    have been so often described that it will not be necessary to devote
    much space to them here.
    The front legs (fig. 29 A) have a structure formed by the adjoining
    end] of the tibia and the first tarsal joint, which is called, oil account
    of its use, the (tfciut cleavc,'. It consists (fig. 29 C) of a semi-
    circular notch (dd) in the ba-e of the first tarsal joint provided
    with a comblike row of bristles. A especially modified, flat, movable
    spur (cc), shown in ventral view at B, is so .,itiiated on the end of
    the tibia (Tb) that it closes over the notch when the tarsutis is bent
    toward the tibia. By grasping an antenna between tlhe notch and
    the spur and drawing it through the incloure the bee is able to re-
    move from this sensitive appendage any pollen or particles of dirt
    that may be adhering to it.
    The middle legs (fig. 29 D) present no special modifications of any
    importance. It will be oblserved, however, that they, as well as the
    other legs (A and F), have the first joint of the tarsutis (ITar) very
    gre;Itily enlarged.
    Tlie hind legs of all three forms, the worker (F), tlhe queen (E), and
    the drone (H), have both the tibia and the large basal segment of
    tlie tarsuis very much flattened. Iii the queen and (drolle there seems
    to be no special ise, made of these l)arts, bitt in the worker each of
    t liese two sentiments is modified into a very important organ. The
    outer surface of the tibia (F, Tb) is fringed on each edge b)y a row of
    long cuirved hairs. These constitute a, sort of basket ((C'b) in which
    tlie pollen collected firoiii flowers is carried to the hive. Tle struc-
    till'(s ;ire lknowni as the o1<' b1.''/.4v, or c1' -Nitln. The inner sir-
    face of the large. flat, ;as;ial segiment of the tarsus (1T7r) is pro-
    vided with several rows,, of short stiff spiiies (G) formlinlg a brush by
    mncails of which the bee gatllers-, thie pollen from' its )od(ly, slice it
    ofteii becomiies covered withii this d(ist frionm tlie flow\e'rs it visits for
    the purpose of geitiig nectar. Wienl a Sifflicient aimolint is accimu-
    lhated on tlhe Ibrlsli1hes it is scriapedl off from eicli over tlhe edge of the
    tibim of thie opl)osite hind leg and is thus stored in tlie pollen baskets.
    Ilelice the worker often flies back to the hive with a great mass of



    ,~ Tb



    Ti r

    ' Tar







    Fr.. 29.-A, left front leg of worker, anterior view, .sliwing position of notch (dd) of
    antenna cleaner on base of first tarsal joint (iTar) and of (closin-" spine (cc) on end
    of tibia (Tb) ; B, spine of antenna cleaner (cc) in flat view; C, details of antenna
    cleaner; D, left middle leg of worker, anterior view; E, left hind leg of iiueen. anterior
    or outer view ; F17, left hind log of worker, anterior or outer view, showing the pollen
    basket (Cb) on outer surface of tibia (Tb) ; G, inner view of first tarsal .ii;iil of hind
    leg of worker sliowin rows of pollen-;-athvrin g hairs ;niil the so-called "wax shears"
    (ff-; II, left hind leg of drJrwe. anterior or outer view.



    pollen adhering to each of its hind legs. Tle pollen baskets are
    also made u.-e o()f for carTving proplolis.
    Between the end.. of the hind tibia (Tb) and the first tarsal joint
    (ITar) is a sort of pincerlike cleft (F and G, ff) guarded by a row
    of short spine- on the tibial edge. This is popularly known as the
    " wax shears" and it is supposed to be used for picking the plates
    of wax out of the wax 1)ockets of the abdominal segments. The
    writer, however, hlas watched bees. take the wax from their abdomen
    and in tlhe-,e observations they always poked the wax plates loose






    I I


    I'lil;. :;d'. 'rsi;l view of ',ld ,f last tarsal joint of first foot (Tar), the claws (Cla),
    and i!iil)(Iiillin (1:1110) of worker; B, ventral view tift' same; C, lateral' view of same,
    s1hwIving .iniimliiuil in ordinary position wihen not in use.

    with lthe ordinary hairs or spines of tlhe tibia' or tarsi and then by
    inu':Ilns of the feel 1pas,ed them forward beneath the body to the

    Tihe last tarsal joint of eacli leg bears a pair of <1(aw.' (E, Cla" and
    ; single iiidi;in ii ,l ulrni (Eip). Eacli one of tlhe claws is bi-
    lIot l, C,,tiiii- of a long talringi outer point and a smaller inner
    o,(' (fig.. :(1 and 31). The claws o()f tlIe worker (fig. 31 A) and the
    (ileel (B) are nly liv.ghtly diffeit'vii in details of oitline, although
    tlhe claw\ of thle (liucln a-lc l1ichl greater ill size than those of the



    worker, but the drone's claws (C) are large and1 very '.-iii1inrly
    different in shape from tlio-e of either tlie worker or tihe qile.i..
    The empodium (fig. 30 A. B, and C, Eip) c(O-isi, of I ternlilal
    lobe bent upward between the claws (C) aild dee)lyv cleft ()il its
    dorsal surface (A), and of a thick baial stalk
    whose walls contain a number of chitinous s
    plates. One of these plate, is dorsal (A and .
    C, hh) and bears five very long, thick, curved
    hairs projecting posteriorly over the terminal
    lobe, while a ventral plate (B and C, ii) is
    provided with nilumerous short thick spine-. ;t-
    A third plate (A, B, and C, gg) almost '
    encircles the front of the terminal lobe, its B
    upper ends reaching to the lips of the cleft.
    When the bee walks on any ordinary sur-
    face it uses only its claws for maintaining a
    foothold, but when it finds itself on a smooth, / ---
    slippery surface like glass the claws are of no
    avail and the empodia are provided for such
    emergencies as this. The terminal lobe is FG 31.-A, outer view of
    pressed down against the -inooth -iur'face and hind claw of worker; B,
    its lateral halves are flattened out and adhere same of queen; C, same
    of drone.
    by a sticky liquid excreted upon them by
    glands said to be situated in front of them. On the relaxation of
    the muscle that flattens the empodial lobes the latter spring back
    into their original position by the elasticity of the chitinous band
    (gg) in their walls.

    The abJomen of the worker and queen appears to consist of six seg-
    ments (figs. 1, 32, 33, II-VII), but it must be reinembered that, as
    has already been explained, the thoracic division of the body in the
    Hymenoptera includes one segment, the propodeum or median seg-
    ment, which really belongs to the abdomen and is its true first seg-
    ment according to the arrangement in all other insects. Hence,
    counting the propodeum (figs. 21 and 32, IT) as the first, we find
    seven exposed abdominal segments in the worker and queen and
    nine in the drone. Each one except the first consists of a tergum
    (T) and a sternum (S), the former reaching far down on the side
    of the segment, where it carries the spiracle (Sp) and overlaps the
    edge of the sternum. The two plates of the last or seventh -egment
    in the worker and queen are separated by a cleft on each side, and
    if they are spread apart it is seen that the tip of the abdomen



    iiiclo-e,, a cavity which lodges the sting and its accessory parts. The
    end] of the abdoineii of the male (fig. 56 D) is quite different from
    that of the female, while in it parts at least of nine segments are

    Fit. 32.-Lateral view of nbdinen of worker, showing the propodeum
    of im, abdomen, of which it is the true first segment.
    visible, the last is very much modified and is exposed
    sides and below.
    An internal view of the ventral plates and the lateral

    .f StnPIp
    Si n-
    I,',; :;:; -Ventral vi.\%v I" ;alltIoziezi of
    worker, i,,,uig tip of Sting (Sin) andl
    ,li ii l'. -ikvr ; I) l'(l;vg (xl'i u l'lp) l i'ii.
    jl', lil. fr, st ill- ', liinilii'r v i lii
    HCvCon lli ,-,,',|irl||i (I'//),

    (IT) as a part

    only on the

    parts of the

    I'i;. 3-.-Dorsail view of !il-
    dominal sterna of drone,
    shlm\iiig Zclaisping ippendages
    (0'0I4.i and 2C'l'p) uof ninth
    .SC1 llll'll '.

    tei',_ii in the worker is sliowvn by figire 0, while a corresponding
    view of 1 ll, i4i il e 1 :el'Ji i- :-]iown by iigiure 31. It will 1)e seeIli that
    e421W ste'nTiM i very'' widely ziinderlapped (viewed from above) by the



    one next in front of it and that the interse'glliental membeialln e (3ib)
    is reflected from the middle of the dor5sal s1urfice of to (le,
    interior edge of the following sternum. By removing an individual
    plate (fig. 35 A) this is more es,,ily shown. It is al,, clea;Irly seen
    that the transverse line of attachment of the nt[enbralie (.1/b) diiilves
    the sternum into a posterior part (Rd), which is merely a prolongedl
    reduplication underlapping the following siternumin and into an an-
    terior part underlapped by the prceding st('rnumi. The posAerior
    half is, hence, purely external while the anterior half forms the true
    ventral wall of the -se,-'ment, its dorsal face being internal and its
    ventral face external. The anterior part is also very smooth and
    shiny and somewhat bilobe'dl and for this reason it is sometimes called
    the mirrors." Its edge is bounded by a thickened ride, giving off a
    short apodeme (A.p) on each side. The mirrors of the last four
    stern are also, and more appropriately, called the wax plates because
    the wax is formed by a layer of cells lying over them. It accumu-
    lates on the ventral side in the pocket between the wax plates and the
    posterior underlapping prolongation of the preceding sternum. Wax
    is formed only on the last four visible segments, i. e., on segments
    IV-VII, inclusive.
    In studying any part of the body wall of an insect it must always
    be borne in mind that the chitin is originally simply an external cutic-
    ular layer of a true cellular skin or epidermis (erroneously called
    hypodermiss" in insects), but that in the adult stage the latter
    almost everywhere disappears as a distinct epithelium. Thus the
    chitin comes to be itself practically the entire body wall, the cell layer
    being reduced to a very inconspicuous membrane. However, in cer-
    tain places the epithelium may be developed for special purposes.
    This is the case with that over the wax plates which forms a thick
    layer of cells that secrete the wax and constitute the so-called wax
    'glands. The wax is fir-t secreted in a liquid condition and is ex-
    truded through minute pores in the wax plates of the sterna, harden-
    ing on their under surfaces into the little plates of solid wax with
    which every bee keeper is acquainted.
    The secretion of the wax has been studied by Dreyling (1903), who
    made histological sections through the glands at different times in
    the life of the bee. He found that in young, freshly emerged( workers
    the epidermis of the wax plates consists of a simple layer of ordinary
    epithelial cells. As the activities of the bee increase, however, these
    cells elongate while clear spaces appear between them and, when the
    highest development is reached, the epithelium consists. of a thick
    layer of very long cells with liquid wax stored in the spaces between
    them. In old age most of the cells become small again and in those
    bees that live over the winter the epithelium degenerates to a simple
    sheet of nucleated plasma showing no cell boundaries. It is thus
    evident that the secretion of wax is best performed during the prime


    S -
    of life. which in bees is at about 17 days of age or before, and that
    old bees can only gather honey and pollen. Bees do not normally
    f-ecrete wax while performing the other more ordinary duties of their
    life. When comb is needed a large number of young bees or bees.
    that have not passed their prime hang together in vertical sheets
    or festoons within the hive and are fed an abundance of honey. After
    about twenty-four hours they begin to construct comb. During this
    t ime the wax is excreted through the wax plates and accumulates in
    the external wax pockets below.
    Ap It is poked out of these pockets by
    means of the spines on the feet
    and is passed forward beneath the
    Rd body to the mandibles. By means
    'S .'of these organs it is manipulated
    A into little pellets and modeled
    X into the comb. Dreyling describes
    AP the pores of the wax plates as ex-
    ces-ively fine, vertical, parallel
    canals only visible in very thin
    sections and under the highest
    -e .Rstope.
    V ---- --- ) power of the microscope.
    Corresponding abdominal sterna
    B present quite different shapes in
    I p. the three forms of the bee (fig. 35
    A, B, and C). In the queen (B)
    the sterna are much longer than in
    ____ the worker (A), while in the
    --R drone (C) they are shorter and
    have very long lateral apodemes
    Fie.. >5.-Dorsal surface of sixth ibdnminal (1l/).
    sternum : A. worker; B, iquen ; C. drone ; The last three abdominal seg-
    sliowing division of platv by line o(if at- i g i. i
    tachment of int.stgmni-intnl membrane ments-the eighth. intil and
    (.1ib) into antiior Imrt with poIished tenth-are very different in the
    internal ,urfavI. in worker b;aring Nwax two sexes oil account. of their
    mgl d(1., and inil lrg, posterior external
    part (Rd) uindir1:lipping :intriior half of moddificationll in each to accom-
    se,'...ding sternum. morlate the external organs of re-
    prd(uction aiid eirg laying. In the female these segments are entirely
    (,'iic'ield within the .:c\-evtll, but, in tlie male, parts of both the
    eighth and ninth segments are visible externally.
    Tlir, ,venth etl rivncnt, of the drone (counting thle propodeum as
    lihe first) i-, thlie l l noriial segnlelit, i. e., the last one having a conm-
    pllete teigium a11d stenlum resem1ling those of the anterior part of
    the allomielt (fig. o(; D, VIIT and VIIS). Behind tlie seventhli ter-
    gliti ;a1id partly concealed within it is the eighth tergiiii (VItIT)
    i'lrrying th. last abdomiinal spiracles (Sp). The eighth sternumn is




    almost, entirely concealed within the seveiit i. It ik very narrow
    below, but is expanded at the upper parts of its i(( (V/IN) wheS
    it is partly visible below the eighth tergiiin and lbelinId the seventh
    sternum. The dorsal part of the ninth segmentlt is membllranlolls except
    for a small apodenie-bearing plate on each side hidden withinil tle
    eighth tergum. The ninth sternum, on tlie other hand, is a well-
    developed semiicircular band (IXS) forli 1mig the ventral and venltro-
    lateral parts of the ninth segment. It bears on each .ide two con-
    spicuous lobes-one a small, darkly chitinize(d, do()r-;1 plate (1C.f'v)
    carrying a large bunch of long hairs, the other a large, thin. veintral
    plate (2Cl.p). Between these four appendicular lobes is ordinarily a
    deep cavity, which is the invaginated penis (fig. 56 E), but in
    figure D this organ is shown partly evaginated (Pn). While the
    penis is really an external organ, the details of its structure will be
    described later in connection with the interimdal orians of reproduction.
    The tenth segment is entirely lacking in segmental form. The anal
    opening is situated in a transverse membrane beneath the eightli ter-
    gum (VIIIT), and below it is a thin chitinous plate, which may
    belong to the tenth segment.
    In many insects the modification of the terminal segment, of the
    males in connection with the futection of copulation is much greater
    than in the bee. The ninth segment often forms a conspicuous
    enlargement called the liypopygiim, which is usually provided with
    variously developed clasping organs in the form of appendicular
    plates and hooks.
    The development of the external genital parts of the drone has been
    described by both Michaelis (1900) and Zander (1900). A small
    depression first appears on the under surface of the ninth segment of
    the larva shortly after hatching. Soon two little processes grow
    backward from the anterior wall of this pouch and divide each into
    two. The part of the larval sternum in front of the pouch become.-
    the ninth sternum of the adult, while the two processes on each side
    form the upper and lower appendicular lobes (the val',a f,,a,,,a and
    the 'alva interna of Zander). The penis at first consists of two little
    processes which arise between the valve interim', but is eventually
    formed mostly from a deep invagination that grows forward between
    them. These four processes arising on the ventral side of the ninth
    segment of the male larva are certainly very surggestive of the similar
    ones that are formed in the same way on the same segment of the
    female and which develop into the second and third gonapophyses
    of the sting. If they are the same morphologically we must homol-
    ogize the two clasping lobes of the ninth sternum in the male with
    the two gonapophyses of this segment in the female. Zander (1900)
    argues against such a conclusion on the ground that the genital pouch
    is situated near the anterior edge of the segment in the female and



    posteriorly in the male. while the parts in the two sexes develop
    later in an absolutely different manner. These arguments, how-
    ever, do not seeni very forcible-in the earliest stages the processes
    certainly look alike in the two sexes.
    The sting of the bee is situated in the sting cavity at the end of the
    abdomen, fromn which it can be quickly protruded when occasion de-
    mands. This sting chamber contains also the reduced and modified
    sclerites of the eighth, ninth, and tenth abdominal segments. In
    fact. the sting chamber is formed by an infolding of these three seg-
    ments into the seventh. It is consequently not a part of the true in-
    terior of the body or body cavity which contains the viscera, but is
    simply a sunken and inclosed part of the exterior, in the same sense
    that the oven of a stove is not a part of the real inside of the stove.
    Consequently the parts of the sting, though normally hidden from
    view, are really external structures.
    A very gentle pull on the tip of tlhe sting is sufficient to remove it
    from its chamber, but a sting thus extracted brings along with it the
    ninth and tenth segments, most of the eighth segment, the poison
    glands, and the terminal part of the alimentary canal. This is due
    to the fact that the inclosed segments are attached to the surround-
    ing parts by very delicate membranes. For the same reason they so
    easily tear from the living bee as the latter hurriedly leaves its victim
    after stinging. The worker thus inflicts a temporary wound and
    pain at the cost of its own life. Undoubtedly, however, nature re-
    gards the damage to the enemy as of more importance to the bee
    community as a whole than the loss of one or a dozen of its members.
    The entire stillngil apparatus with a ba- of poison attached is thus
    left sticking in the wound while tlhe muscles, which keep on working
    automatically, continue to drive the sting in deeper and deeper and
    at the sanme time pm1)ip in more poison. Siuch a provision certainly
    prodliuces much more effective results than would a bee giving a thrust
    hte'e and another there with its sting and then rapidly flying away
    to escape from danger.
    The sti itslf, when extracted fr itsits clamber, is seen to con-
    sist of a straight tapering slhaft with its tip directed posteriorly and
    it, I,;ise swollen into a bulblike enlarIement. Tn siuperficinl appear-
    ln,.c t1he slhaft appears to be solid, although we shall presently show
    tliat it is not. but the bulb is clearly hollow and is open below by
    a distinct medi:111 cleft. Several plates of definite shape and arrangike-
    ilii'1t alw;a'y. remain attached to the sting anld ()overlap its base. Tle
    entire a apparatius, including the base o(f tlie large lpoiso sac, is sli owvi
    si,,,wlut t diaatra lmat ically in side view by fi,,gre 3;. The bull) of
    Ilie ,tiig (,/ih) is coit iected with tlie lateral plates by two '1 arls
    which (cu'\'ve outtward ;,i Il upward f'ron, its base. (Otly tlhe left side
    i -huiown iii the figure.) Between these arms the two poison glands



    (PsnSc and BGl) open into the anterior end of the bulb. From il,(.
    posterior ends of the plates two whitish fillgerlike processes (Sf ,iPp)
    project backward. When the sting is retracted these lie at the -idlvs
    of the shaft (figs. 33 and 37), but in figure 36 the' sting is shown in aI
    partly protracted position. These appendages, often called( the stillg
    p)alpi, undoubtedly contain .-ense organs of ..onme -ort. by means of
    which the bee can tell when her abdomen is in contact with tlhe object
    upon which she des..ires to use her sting.
    A close examination of the sting shows that it is a much more comn-
    plicated structure than it at first sight appears to be. The shaft, for
    example, is not a simple, solid, tapering, spearlike rod, but is a hollow
    organ made of three pieces which surround a central canal. One of
    these pieces is dorsal (fig. 36, ShS) and is the true prolongation of
    the bulb (ShB), while the other two (Let) are ventral and slide
    lengthwise on tracklike ridges of the dorsal piece. Moreover, each
    basal arm of the
    sting is double, con- x
    ZD . s Sc /
    sisting of a dorsal //
    or posterior piece u fi / SmP- 36).
    (ShA), which is like- | (- -
    wise a prolongation >T h.-,.^^
    of the bulb, and a -
    1 1 i r-W^> // \ Ob .^-X
    ventral or anterior
    piece (Lct), which is B6 K sf -
    continuous with the ,,-.ShS(T2C)
    ventral rod of the Lc.
    shaft on the same FIG. 36.-Sen ii:ingranmmnatic view of loft side of stin r of
    side. Hence the sting worker, accessory plates (Tri, Ob, QI), stin-" i.i1,i's
    (StnJ'lp), alkaline poison gland (BGl), and base of large
    may be analyzed into poison sac (i'.snSc) of acid gland.
    three elements, which
    are characterized as follows: The dorsal piece, known as the sheath,
    consists of a prominent basal swelling or bulb (ShB) containing a
    large cavity, of a terminal tapering shaft (ShS), and of two curved
    basal arms (ShA). The ventral part consists of two long slender
    rods, called the lancets or darts (Lct), which slide freely upon two
    tracks on the ventral edges of the sheath and diverge upon continua-
    tions of these tracks along the basal arms of the latter (ShA). The
    bulb is hollow, containing a large cavity formed by invagination
    from below, where it is open to the exterior by a lengthwise cleft.
    This cavity continues also through the entire length of the shaft of
    the sting as a channel inclosed between the dorsal sheath and the
    latero-ventral lancets. This channel, as will be explained later, is
    the poison canal of the sting.
    Each arm of the sheath (Sh.1) is supported at its end farthest
    from the bulb by an oblong plate (fig. 36, Ob), which normally over-



    T-T v i yrn\ rv% rxTrCv T-m ni xvv D v V

    I |t ILL ... I I ..' L 1IL t L,.*, l l .lL l m LJ JI J2. e

    lap), thle -ide of thile bIlb), and which carries distally the palpi of the
    sting (StPlp). Each lancet is attached at its base to a triangular
    jift (Tr;) which lies latero-dorsad to the base of the oblong plate
    and articulate-s withl a knob on the dorsal edge of the latter by its
    veiitral posterior angle. By its dorsal posterior angle the triangular
    pldate is articulated to a much larger qumdratce plate (Qd) which
    ovrliaps the distal half of the oblong plate. A thick menibra nous
    lobe (IXS), concave below, where it is thickly set with long hairs.
    overlaps the buIb) of the stinllg and is attachlied on each side to tle
    e(dges of the oblong plate-. All of these parts are shown flattened out
    in ventral view by
    -,Zrb figure 37.
    The presence of
    StnPIpi., the two basal arms
    of the sheath might

    ^^-^ (f^ zn^^c h ^"^P1
    sugg est that this
    part is to be re-
    garded as made tII)
    I:. /Iof fused lateral
    once: v halves. In this case
    Odi 1il' we should have six
    "iappen-dicular- ele-
    htl \vit,!,i mlon ents. viz, the two
    lta I ncets. th e two
    halves of the sheatlih,
    4 ..Tri and the two paIl-
    tS 1)T1slike organs. If
    v now we trn ie ack to
    figure 8, showingr
    got"- \ -c aIpot the l com lonent parts
    B t oeShA of the ovipositor of
    a lomgorned grass-
    i.i'i;. :;7.-Vcntri1 view oIf stinl of worker and accessory parts. hloppei, we call not
    I1:1IT t'nI'd Out.
    fail to be struck at
    ti(P' by thei we tat .- iiijjii tV alh irity Itllw( ths or n a thle sting of
    Stlie bee (fig.r : T) The first-n go re)popliAses (1G) of fie ovipositoi are
    identic.] % tii thle li, Ickt (Lct) of the stiiog, alnd their 1 sliding co'nec-
    tion, b. l' t 'a,- of l,.'i-itudidi 11 tra'kds. witli tllie set i(ld g(niI)a l)l)iyses
    ( ,,') s ,'IIAgt at ()mice flat flie hittl| el l eprcsent tlie slivatl i of the
    stinjg (S,.). The ideititv i.,, .-,ill I1m(r, At'oigly( Slur'e, ted whlell we
    (I)-,'I.'Vc the -11:11] ,tlb) (1) 1,) frun led by the ft,,ted lots of these
    i If lolUlv-es.- 1 T I' tM ic .I4,1i iii al, i .-VMS (.;('r), wvl icll i ldlosv 0,t'c, ) t vIi
    t thi e H ticr alrt s of the oxi i)p-iit ', rejwe-eiit tlie l)all i of tie
    -iitl ( / p 11,/),1). If n tilv., \we ..tI:l ( lit' vl(,VIt v (lllit't of t 1ev parts .of
    flit' siligr \%t' are riviin'udlc~ tha't INIi iiiiilaritv 1):'twelt'lic teStim ligdI(
    Uii (I'i1)(-itoII~l. s "ollict[l~riii~ hig mii-eu -Il i ccIldeiital i'esemIllAiice


    between two different organ --iii fact we c;mi not d(1wil)t tl;it thel sti1g
    is simply an ovipositor which, being no longer ii(eeded for egg-layvingr
    purposes, has been modified into a pooi-l-injecting appar;atii-. Zan-
    der (1899, 1900) and other, have shown that the sting of the bee
    arises from six little abdominal procesv-es of the larva, two of which
    arise on the eighth seQgmlent and four on the ninth. Those of the first
    pair develop into the lancets, tho-c of the middle pair on the ninth
    segment fuse to form tlhe -heath, while tho-e of thel outer pair be-
    come the palpi. The ovipositor, it will be reelnterl l)ied, develol)ps in
    the lower insects from two pairs of proce--e- arising on the eighth
    and ninth abdominal sterna, the second piir of Which very soon
    splits into four processes. The simultaneous appearance of six on
    the bee larva is simply an example of the hurrying proce- or accelera-
    tion that the embryos and voting of most higher forms exhibit in
    their development.
    It i: only the higher members of the Ilymnenoptera, such as the
    wasps and the bees and their close relative-. that pos-e-s a true -ting.
    The females of the lower members have ovipo-itors which closely re-
    semble those of such insects as the katydids, crickets, and cicadas, but
    which, at the same time. are unque-tionably the same as the sting of
    the stinging Hymenoptera. It is said that the queen bee makes use
    of her sting in placing her eggs in the cells, but both the wasps and
    the bees deposit their eggs in cells or cavities that are large enough to
    admit the entire abdomen, and so they have but little use for an egg-
    placing instrument. But the females of the katydids and related
    forms like Conorephalus (fig. 8) use their ovipositors for making a
    slit in the bark of a twig and for pushing their eggs into this cavity.
    The cicada and the -awfly do the same thing, while the parasitic
    Hymenoptera often have extremely long and -lender piercing oviposi-
    tors for inserting their eggs into the living bodie- of other in-ect-.
    An examination of the sting in place within the -ting chamber, as
    shown by figure 41, will suggest what the accessory plates represent in
    other less modified insects. It has already been explained that the last
    external segment of the female abdomen (fig. 32, VII) is the seventh.
    Within the dorsal part of the sting chamber is a slight suggestion of
    the eighth tergum (fig. 41, VIIIT), which laterally is chitinized as a
    conspicuous plate bearing the last or eighth abdominal spiracle (Sp).
    The triangular plate (Tri), as Zander has shown by a study of its
    development, is a remnant of the eighth sternum, and the fact that it
    carries the lancet (Let) shows that even in the adult this appendage
    belongs to the eighth -egment. The quadrate plate (Qd), since it is
    overlapped by the spiracle plate- of the eighth tergum, might appear
    to belong to the eighth sternum, but Zander has -hown that, by its
    development, it is a part of the ninth tergum. In many other adult
    Hymenoptera, moreover, the quadrate plate- are undoubtedly tergal,



    fort they are -!,oietiine-- connected by a bridge behind the eighth
    teriimi. Tihe oblong plate (Ob) and its stalk represent the ninth
    sternumt and since it carries both the arm of the sheath (ShA) and
    the palp)us (Pip) it still maintains its original relationships to the
    gonapophyses. The mnembranous lobe arising from between the
    oblong plates and overlapping the bulb of the sting (figs. 36 and 37,
    IXS) mii-t belong to the median part of the ninth sternum.
    The tenth segment (fig. 41, X) consists of a short, thick tube having
    the anus (An) at its tip. It takes no part in the formation of the
    sting, but is entirely inclosed in the dorsal part of the sting chamber
    beneath the seventh tergum.
    In the accessory plates of the bee's sting we have a most excellent
    illustration of how the parts of a segment may become modified to
    meet the requirements of a special function, and also an example
    of how nature is ever reluctant to create any new organ, preferring
    rather to make over some already existing structure into something
    that will serve a new purpose.
    There are four glands connected with the sting, two of which
    are known to secrete the poison, which is forced through the canal
    between the sheath and the lancets and ejected into the wound made
    by tlhe latter. It is this poison that causes the pain and inflammation
    in the wound from a bee's sting, which would never result from a
    mere puncture. The other two glands have been described as lubri-
    cating glands," being supposed to secrete a liquid which keeps the
    parts of the sting mechanismn free from friction. They lie within
    the body cavity, one on each side against the upper edge of the
    qtiadrate plate, where they are easily seen in an extracted sting, each
    being a small oblong or ovate whitish cellular mass. Transverse
    microtome sections through this region show that each of these
    glands opens into a pouch of the membrane between the quadrate
    plate an(d tlhe spiracle-bearing plate of tlhe eighth tergum. Each
    gland cell commninicates with this pouch by a delicate individual
    duct. The secretion of the glands is thus poured upon the outer sur-
    face- of the quadrate plates and might easily run down upon the
    ba,.s of the lancets and the armnis of tihe sheath, but, for all that, the
    notion that it is hlubricatl ive in function is probably entirely conjectural.
    The Inrge. conspicuous p(ii-)n sac (figs. 36., 37, 41, ;and 57, '/sSe-)
    that opens by a narrow nieck into the anterior end of the bulb of the
    sting i., well kMownN to everyonle at all acquainted with bees. The
    poi-oll wli'ich it cotains conies from tihe delicate branched thread
    attt;acled to its anterior end (fig. 57), a minute tube which, if traced
    forward a short distance fro)i tlhe. sac. will be seel to divide into two
    brainchlie., whiichli aric lmr and much coiled anid convoluted, each ter-
    milt infi fiallyV in a small oval enlargement (A 0I1). These terminal
    s\el lings- a ,1 geerally regarded as tlhe true glands and the tubes


    TilE ABDOMKX, W.AX (;I..\ANS, AND S.1 ING. 79

    (A 47D) as their (lu<'-. but the epitheliuI [ of the tubes apppea i- to bl
    of a secretary nature al-,, and, if it i- not, it i- hard to i i any re;:s in
    for their great len.l2th. It ;al-o does not look ;.
    probable that the two little end bodi,- could BM-
    form all the poi:-on that fills, the comparatively ',
    enormous; sac. Nu --J "2
    Thv walls of the poi-on -ac (fig. 38) are lineil .'.
    by a thick coat of laminated chitin (I1t) thrown Ep t
    into numerous high folds. In the neck pirt of_, f
    the ,ac the folds are arnanired very regularly in /
    7 &* '* -: "-~^-
    a transver-e direction and fonir interrupted l,. -Int
    chitinous rings. holding the neck rigidly open.
    The epitheliumn (Epth) contains nuclei (N,) I.
    biut the cell boundalies are very sliglhtly marked.
    Tleiere is a distinct ,a-e(ent membrane (BJ), FI;. 38.-Section of
    forminin- a tunica propria externally, but there small piece of wall of
    poison sac of sting.
    are no muscle fibers of any sort pre-cit except
    a few which are inserted upon the sac from some of the surrounding
    organs, and which apparently act as suspeno()ria.
    Lum The poison found in the sac has an
    SLu acid reaction and is suppo-edl to consist
    principally of formic acid. Hence its
    gland is known as the acid gland (A Gi)
    of the sting.
    The other sting gland is a short, very
    .L ~ inconspicuous, and slightly convoluted
    u whitish tube (figc. 36, 37, 41. and 57,
    CD BG1) opening directly into the base of
    p, \the bulb ventrad to the open ing of the
    Bpoi-on sac. Its walls consist of a thick
    epithelium of distinct cells (fig. 39,
    ? Epth) lined with a thin chitinous in-
    ilDL tima (Int) and surrounded by a distinct
    S-basement membrane (B.1), but, as in
    the other gland, there are no muscles
    Epth---- present. The -retion of this gland is
    Said to be alkaline and the gland is
    'j-p?^I therefore known as the 1l.1,ie gland
    4 (BGl) of the stiiO'.
    Experiments inade by Carlet (1890)
    FIG. 39.-Sections of alkaline uiaud show that it is only the mixture of the
    of tin. product- from the two poison glands
    that is fully effective in stinging properties. Carlet's experiments were
    made upon houseflies and blowflies. He shows (1) that flie-, stung by a
    bee die almost in-tantly, (2) flies artificially inoculated with the secre-



    tion of either gland alone do not die for a long time even in spite of
    the necessary mutilation, while (3) successive inoculations of the
    same fly fir-t from one gland and then from the other produce death
    in a much shorter time than when inoculated from one gland alone-
    pre-Inmbly as soon as the two liquids mix within the body.
    The two secretions. one acid and the other alkaline, are poured
    together into the base of the stino bulb and mix within the cavity
    of the latter. The resulting poison is then driven through the chan-
    nel in the shaft to near the tip of the latter, where it makes its exit
    into the wound. Since the large poison sac is not muscular, the poison
    is not forced through the sting by it, as is often supposed. A glance
    at figmlire 57 (see p. 135) will show that the accessory plates of the sting
    support several very compact sets of muscles on their inner faces.
    These muscles so act during the process of stinging that the triangular
    plate- (figs. :3; and 37, Tri) turn upon their hinge-joint articulations
    with the oblong plates (Ob). By this motion of the triangular
    plates the attached lancets (Lrft) are moved back and forth along
    the tracks on the lower edges of tlhe sheath and its arms (ShA).
    Each of these tracks consists of a ridge with a constricted base which
    dovetails into a correspondingly shaped groove on the dorsal surface
    of the lancet. This structure, as s-een in cross sections through the
    ,shaft and bulb of the sting, is shown by fig. 40 A. B, and C. The
    laincets are thus held firmly in place, while at the same time they may
    slide hack and forth with perfect freedom. The figures show also
    that all three parts of the sting are hollow, each containing a pro-
    longation (be) of the body cavity. Between them. however, is in-
    closed another cavity through which the poison flows. This is the
    po;xon canal (PI.n(J). In the bulb (fig. 40 C) the body cavity is.
    reduced to a narrow cleft (be) by the great size of tlhe invaginated
    poisoll c.1'.1al (P.,/,C).
    It will now be most convenient to describe the apparatus by means
    of which the poison is ejected from the sting. As before pointed out,
    tlhe large poi,,so sac can have no functions in this connection because
    its walls are entirely devoid of muscle fibers. On the other hand,
    there is aii actual pumping apparatus situated within the bulb. This
    consists of two pouchlike lobes, having their cowncavities directed
    1",-teriorly, attached to tlie upper tdg''s of tlhe lancets (fig. 40 D and
    (, I'l7') oI the anterior end-, of the parts of thlie latter which slide
    within the lower edges of the bulb chamber. The lobes lie side by
    side wi lIi in the bub111) (fig. 40 C, VI v), when tlhe lancets are in the same
    1o()sitionl, and ea(ch lhas aII accessory ahiiiiia against its vowni inner wall.
    \\liii the lanc .ts are pushed backward tlhe walls of the lobes flare
    :11ii :14railiiil-t the oisol contaiiledl in the 1) bulb) and drive this liquid
    I,4f14`'1 thile into tle ,.lanni,,el1 of tlhe slhaft, while at the same time they
    s.,tek ioire oi.soI into thlie front of the bulb from the glands. When,


    or the other hand, the lancets are reiracted the pouclies'e- (-.llapi- so
    that they mnay be drawn back through the poison-filled bulb without
    resistance, but they are ready for action a gail ;is .O001 as -, ic l(move-
    nment of tlhe lancets is reversed. The whole apparatus thfis consti-
    tiites an actual force pump in which the lobJes on the lancets alter-
    nately act as a pistoii and as valves. The lancets need not work
    together; in fact,
    they more often S
    lperhalps wor)l al- PnC" Brb
    terniiately, the lol)bes bC vv iB B
    ib)eingr of such a A ,S
    size as to be ef-
    feet ive either when *"N ShS
    acting together or 00.,
    separately. ShS Ln J
    The reader ac- tS"
    quainted with B t H l
    other works on D '
    the anatomy of ShB. ,bc
    the bee. such as V lv
    those of Cheshire lVtvs
    (1886), Cook
    (1904), Cowan
    t(1904), and Arn- co
    lhart (1906), will -Pnc
    see often repeated
    the statement that Ld CG
    the poison leaves Fie. 40.-Details of sting of worker: A, section through tip of
    sting showing lancets (Let) and shaft of sheath (sh.s) sur-
    the sting both by r.,undling central poison canal (Psno), and each containing
    a ventral opening a prolongation of the body-cavity (be) ; B, section of same
    Sa o in near base of bulb; C, section of sting through basal bulb,
    between the lan- showing poison canal as largo invaninated cavity (J'stnC)
    ets near their tis in bulb of sheath (ShB) containing the two valves (Viv)
    S! h t of lancets (Let) ; D, part of left lancet carrying valve (Vlv),
    and by several lat- dorsal view; E, tip of lancet showing pores opening on
    eral pores near the bases of barbs (oo) coming from body-cavity (be) of lancet-
    not from poison canal; F, dorsal view of shaft of sheath
    ends of the lancets showing lateral series of pores (oo) from prolongation of
    opening from the body-cavity (be) ; G, lateral view of left valve and part of
    1 tolancet.
    1)oison canal upon lancet.
    the bases of the barbs. The writer, however, has never been able
    to observe the exit of the poison from any such lateral pores, while,
    on the other hand, it is very easy to watch it exude from between
    the lancets on the ventral side of the sting near the tip. If an
    excited bee is held beneath a microscope and the tip of the sting
    observed, the poison will be seen to accumulate in little drops near
    the tip on the ventral side. If, also, the bulb of an extracted sting
    22181-No. 18-10----6



    b)e -(lueezed gently between a pair of forceps the poison will be seen
    to emerge in the same way. In fact. it can be actually squirted out
    by a sudden compression when the bull) is well filled with poison, but
    there i: never any evidence of its escape through the sides.
    All examination of the end of each lancet does reveal a number of
    obliqi(e pores (fig. 40 E, oo) which have beeii figured by other writ-
    ers. and they certainly open on the 1)a-es of the barbs as described,
    but their inner ends apparently communicate with the body cavity
    (be) of tlhe lancet instead of passing clear through the lancet and
    opening into the poisoni canal. Furthermore, a paired series of
    exactly similar pores extends the entire lenigtlh of the shaft of the
    sheath (fig. 40 F, oo), opening on its dorsal surface from the body
    cavity (be). No one could possibly claim that the poison emerges

    -"i .
    PsnSc > '::T

    .. T bTra


    J:~ -An


    YiE;. 41.-Tip of nhilomon of worker with loft side romovird showinL: rlrlit halves of sev-
    enth teruinm (WlIT) and sternum (VII8), in taihihgi the sling clinihim r (kAk) cut open
    alotnlz the line '"'. 0XpOsi ng the eighitii terminl (vm1"/Yi', tlie rudimentary tentli segment
    (X) carrying flie anus (An), ;ind h(le ,tiiiu and accessory 1i-Lrts shown ly fig. t ig .
    also through thesv porves, which. very curiously, (10 not appear to
    hayve beenl des-cribed before. althloui0h t hey are e vell Imiore colspicu(olls
    as well ,I.,M 1e umierouis t111an those of the lancets. The writer hias
    nI(ot be eth success-fuil in preparing hlistolooical sections of tlie sti ng
    wvhliclh show tllvhi' pores. but they prolably constitulte tlWe ducts of
    -oC kiniid of siilwbiticuila' glaO(Ids.
    A Cr(T--s(VCtioan through thIe sti, a shmoiit dista ince il front of its
    tipp slows tIhat tine Il ancet s a t e : e1 s ren p (earated byI a narrow cleft (fig.
    10 A), while hvlsaewlneI (B aund C) t a ey are sor t tigulolus. This cleft
    b., weelln tile ('11(kd of tlie lancets forms the exit for tihe poison from the I
    ci i~i ki ,d ofsIl(.i'.rIl, s
    10ane.\) \\!l .s\'~ c( n )t~yae(mtgo~.Ti 'et

    Th' sting of the (l1f.e.n is Imuc']1 longer than that of tlhe worker
    anld i- mGore solidly attached w\itlhin tle stig(r clihazimber. Its shaft is



    strongly decurved beyond the bulb. 'I''I l;Ii.-e(t li,:vh fewer n11ud
    smaller barbs than thi)(e of the worker, but the two li-,on glr;i1u1
    are well developed (fig. 57, AGI and B(01), whilec the poi,,on ,;itc
    (PsnSc) is especially large.
    A number of minute unicellular glands open upon the
    mental membrane between the seventli and eighth terga of the ,ab-
    domen. These are so ietinieis called the glands of Nassanoff, after
    their discoverer. Nassanoff suggested that they are sweat glands.
    while Zoubareff thought that they form small drop-, of liquid 'aid
    to be excreted by bees during flight derived front the exces of writer
    in the newly collected nectar. Their function, however, has been
    much more carefully investigated by Sladen (1902), who found that
    they are scent organs producing a strong odor even when the part
    of the back to which they are attached is removed from the rest
    of the abdomen. He furthermore identified this smell as the '-alne
    that bees give off when a lot of then are shaken from a frame on
    the ground close to the front of the hive. Under such cirriii-tance-
    also, as in natural swarming or during the first flights in the spring
    or after a period of bad weather, bees are well known to produce a
    peculiar sound called the "joyful hum." Sladen ob:-erved that this
    was produced, in the case of bees shaken before the hive, by those
    individuals who first found the hive entrance, then by those next to
    them, until very soon all the others were informed of the location
    of the entrance and proceeded to make their way in. Also, when a
    swarm loses sight of its queen, those'that find her first set up this
    "joyful hum and immediately the rest of the swarm is attracted
    to the spot. In the springtime the young bees seen to be guided
    in their flights by this same hum of the old ones. Sladen, however,
    observing the odor emitted at the -ame time, thinks that this and
    not the sound is the real means of information, the sound being
    simply incidental to the special movement of the wings produced
    for the purpose of blowing the odor away from the body. He argues
    that we have no evidence of an acute sense of hearing in bees, while
    it is well known that they possess- a delicate -ense of smell located on
    the antenna. This argument certainly seems reasonable, and we
    may at least accept Sladen's theory as the best explanation of the
    function of the glands of Xassanoff.



    It i- no ex-naeration to -ay that eatillg is the most important thing
    that any animal does and that its alimentary canal is the most im-
    portanllt organ it possesses. The entire system suffers when there is a
    (leficiencv in the food supply or an impairment in the digestive appa-
    ratus. Every other function is either subservient to or dependent
    upon that which furniishes nourishment to the cells. The senses of
    sight, smell, and taste are all more or less concerned in the acquisition
    of food. The muscular system enables the animal to hunt for it, to
    dig for it, to climb for it, or to chase living prey either on the ground,
    in the water, or in the air, and to kill, tear, and chew it when ob-
    tained. The blood is the servant of the stomach, for its entire func-
    tion in insects is to carry the products of digestion to the body cells.
    The heart fuirni-,he- the motor power of the blood. The respiratory
    function is accessory to that of digestion, inasmuch as it furnishes the
    oxygen which unites with the waste materials ejected from the cells
    and renders them capable of 1)being removed(l from the blood. This
    removal is accomplished partly by the respiratory system itself and
    partly by special excretory organs. Thus we see that the sense organs
    and the muscular system are the agents that cooperate in obtaining
    the raw food, the digestive tract is the kitchen of the body in which
    the food is prepared for use. the blood is the waiter that distributes
    it, while the respiratory and excretory systems are the refuse gath-
    erers that. remove waste products. The nervous system holds the con-
    trolling power over all the.e organs. It regulates them in the per-
    formance of their duties and coord(linates their actions so that they
    all work together. It makes a Iunified orlga'lisil out of what would
    otlherwi.-e be "imply a complex mass of variously specialized cells.
    The reproduct'ile ftinction alone contributes nothing to the indi-
    vidual. In fnct. tlhe pro(lucti(on of spermatozoa by the male and of
    eggs by the fenimale and thle niourisliing of the embryo and the young
    (reaTte a d(ea1n1.d upon all thlie oilier organs for material which is
    s.eparated from the individual that l)rodflies it. But this is what the
    orgalisi exists for; this is its reason for being. At least this is
    what it a imoiiiit-, to in the case of the individual, though from a wider
    p1)iilosoplhical st.ainddpiint tlie real truth is probal)ly just the reverse,
    \iZ. a;y iV p(ecies, exist. because its individu(l als reproduce themselves.
    ''le writer lhas already made frequent use of the word cell,"
    assuiling that tihe reader is familiar with the meaning of this word
    as .se(dl in ;iatomy and physiologyg. Tlhe entire body of an animal
    or plal:it is 1ade(h, up) of crU1x or their )pro(dIicts. T'le word(, however, is
    mil-eading, for a cell is not a small sac or empty space, as was at



    /'I ^

    Rect 4 _
    FIG. 42.-Alimentary canal of worker (PlJy-Rcfl), tozothr xvit'l )Ilrn.IY ,'al 'L'b (A1 ),
    and salivary glands of head (2Gl) and of thm-nx (.;l). as seen ,by cuttiug body upeu
    from above and pulling the ventricutilus (Vent) out to left.



    first supposed from the study of plants, but is a little protoplasmic
    body or corpuscle, visible only under the microscope, surrounded by
    a membranous cell wall and containing a small internal body called
    the nucleus. The different cells of the body are specialized in groups
    to do some one particular thing-the salivary cells secrete saliva, the
    mu-icle cells contract, the excretory cells pick out waste substances
    from the blood, and so on. But this specialization does not signify
    that each cell does not perform its own vital processes in addition to
    its specialty. The fact that it remains alive and works means that
    the complex chemical components of its body substance or protoplasm
    are constantly being reduced to simpler compounds which are ex-
    pelled, while new protoplasm is built up from the supply of food
    material brought by the blood. This double process of destruction
    and reconstruction is known as metabolism, while its two phases, the
    breakiing-down process and the building-up process, are known as
    k(dtlhbobix.m and a ibolism, respectively.
    Now, while all the cells of the body must have nourishment, none
    of them, except those of the alimentary canal, is capable of utiliz-
    ing the raw food materials that an animal obtains in a state of nature.
    These materials must therefore be changed into some other form in
    order that they may be '.iain71lated by the cells. This change is called
    The single cell composing the body of a Protozoan. living free in
    nature, digests its own food and then assimilates the products of its
    own digel-tion. But, of the cells constituting the body of any mul-
    ticellljiar animal. only those of the alimentary canal are capable of
    digesting raif foodstiffs, and, moreover, aus digestion is the specialty
    of these (ell". they ha ls al-o to digest the food for all the other cells
    of the body.
    The two most important changes that. must be brought about in
    the iinatural food by digestion are those which make it soluble in the
    blood anid which render it capable of passing through animal tissues.
    Ij the first place, the food must (diffuse through the walls of the
    alhiientary canal as a liquid which mixes with the blood, for there
    Nre no pores or o)enings of any sort from the alimentary canal into
    the body cavity; and in the second( place, it must pass through the
    w;ills-, of the c(.ells themselves. I'lie digestive changes result chiefly in
    1a 1reakiing down m of the complex molecules of the raw food materials
    into mtire i..i le chellmicail utibsta'ices. These are taken up by the
    cell. .Ili(d reconstiricted iito comp)llex protoplasmic molecules which
    c.a niot. es ape through the cell ineni)rane until they are again broken
    down ilio siI10l(lr forms.
    T'lie \wast 1 products of the cells consist principally of carbon, hy-
    dlrI',.11. a1d iitro-gei. These arie converted by the oxygen supplied
    by tIle 'espiratory system, into cArbon dioxid, water, and compounds of




    urea. The first, being a gas. mixe.., withl the air iln tlie tr raelidl: ttiIbes
    and so reaches the exterior during exiihalation. Miuchli of tl1, wat ir is-;
    also given off t1hrouih the traclical system i iln thle form of vapor which'
    exhales from the spiracle,. but, since insects are c' oveld by their
    hard c(hitinolis shell, it i, probable that tichey do ii(it "swat." sTlle
    con)mpounds of ureai1, and probably alo so si e water, a re sepa rated
    from the blood by the excretory \ glands, called lalpigli iii, tIubIles
    in insects, which empty their products back into the alimentary
    canal, whence they are di-clja .rged( with the feces from the iiint-tieii.
    Digestion is brought about by substances called ri,.1.yIS which are
    contained in the variious liiquids mixed with the food in the ali ientary
    canal. These liquids are -ecreted by the salivary glands and by the
    cellular walls of the stomach.
    The opening of tlie s-alivary duct on the ba-e of the prolboscis has
    already been de-cribed (see pp. 49-51). T''he true salivary glands, or
    those corresponding with the .alivary glands of other insects, are
    arranged in two )pairs, one situated within the head (figs. 19 and 42,
    2G1) and the other within the thorax (fig. 42, 3G1). The four ducts
    unite into one median tlube, which enters the 1ase of the labiumn (fig.
    19, SaOD) and opens upon the upper surface of the ligula (fig. 15 F,
    and fig. 16, SalDO). The large and conspicuous glands lying within
    the anterior and upper parts of the head and opening into the
    phlarynx will be de-'ribed later in connection with this organ. They
    are special pharyngeal glands in no way homologous with the salivary
    glands of other insects, and are by many supposed to secrete the
    brood food instead of a diges-tive liquid like saliva.
    The salivary glands of the head (Syf( in o. 2 of Cheshire, post-
    i'crcbral gliu<.l of Borda-;) lie against the posterior walls of the
    cranium. In the worker each consists of a looely arranged mna:-s of
    pear-.haped follicles or acini whose individual ducts unite irregu-
    larly with one another and eventually form a coiniton duct on each
    side (figs. 19, 42, and 43 F, 2G1). Their two ducts unite with the
    median duct from the thoracic glands just before the ba-es of the
    mesocephalic pillars (fig. 19). In the drone these glands have a
    quite different appearance from those of the female, each colnsistinlg
    of a compact mass of very small follicles connected by minute ducts
    and flattened against the po-terior walls of the head (fig. 43 B and C,
    2(71). A large lobe of this gland in the drone extends forward on
    each side against the face, between the compound eye and the clypeus
    (fig. 10 C, 2Wl), thus occupying the position of the large mandibular
    gland in the worker (A, LMdGl) and in the queen (B, lJdGl).
    There is also a prominent triangular mass of glandular cells in the
    drone situated just above the ocelli (fig. 10 C, .'G1) which has been


    described by Bordas (1895) as a separate gland opening by two ducts
    into the esophagus just behind the pharynx. The writer, however,
    has been utterly unable to discover any such ducts, though two sus-
    pensorial ligaments of the anterior end of the esophagus are at-
    tached to the wall of the head at the posterior ends .of these glands
    (fig. 11 B, g) and might easily be mistaken for ducts. These post-
    ocellar glands" of Bordas. moreover, appear to be simply detached
    lobes of the postcerebral glands. They are prominent also in the
    queen (fig. 10 B, 2G1) and are represented by a few follicles in the

    "i GI

    Dci~t A Dc c

    .. .4GI


    Pi-;. 43.-A, small piece of large lateral phliaryngeal glands in head of worker; B, piece of
    Ijostcercbral salivary glands in head of drone; C, postcerebral glands (2Gl) in normal
    position against posterior wall of head in drone; D, pharyngeal plate (s) of worker,
    ventral view, showing bases of lateral pharyngeal glands (IG1) and their receptacula
    (mm), and median ventral pliarynreal gland (G0li ; E. corresponding view of pharyngeal
    plate of drone. showing entire absence of lateral pharyngeal glands, and greater devel-
    opmun-nt of ,small median glands (.UG' ; F, part of postcerebral gland of worker.

    Bordas describes the follicles of the postcerebral glands in the
    worker as hollow sacs. each having a large lumen lined with a chiti-
    nous intimai. Their secretion, he says, is a thin viscid liquid, pale
    yellow in color and having a slightly alkaline reaction. According to
    Scbwienz (1qS:I) ea(ch gland is developed as an outgrowth from the
    COllo111011 dtict of tlhe thoracic glands.
    Tlhe salivary glands of the thorax in the bee (Sy8tem No. 3 of
    Clhsliir,. floraa,' .X1',d ury g1inds of Bordas) are the ones that cor-
    rpiTlM1 with thle ordinary salivary glads of other insects. They
    are described by Schielnenz (1883) as being formed inside of the



    outer covering (tunica propria) of the first part of the larval siik
    glands. But it is of common occlurreilee in insects that tli< sali vary
    glands are temporarily specialized as s.ilik-prlducing ojrgans in the
    larva. In the adult worker these glands lie in the ventral part of
    the anterior half of the thorax (fig. 42, 3G1). The two are widely
    separated anteriorly, b)it their posterior eds are contiguous. lach
    pnn-bachd tgloa nds areWe Woniffli. ir.
    consists of a mass of small, many-branched, glandular ti bes op'li Z
    into several collecting ducts which empty into a -ac ii'eir tlie( ante-
    rior end of the gland (II). Fromn each of these reservoirs, thell. a duet
    (DIt) runs forward and fuses with the one from the oppo-ite side
    just within the foranmien magnum of the head. The common duct
    thus formed turns downward within the head, receiving the two ducts
    of the post cerebral salivary glands and then enters the ba-ve of tle
    mentum (figs. 19 and 43 C, SalD), to open as already described on the
    upper side of the ligula at the root of the glossa and between the
    bases of the two paraglossae (fig. 15 F and 16, SalDO). The
    secretion of the thoracic glands is said also to be weakly alkaline.
    Therefore the entire salivary fluid poured out upo)in the labium is
    alkaline, and it must be designed to act especially upon the food
    taken through the proboscis. This action, furthermore, on account of
    the location of the salivary opening, may take place before the food
    enters the mouth.
    The food of the bee consists normally of pollen, nectar, and honey.
    The first is eaten entirely with the mandibles, while the other two are
    taken through the proboscis. The pollen is to the diet of the bee what
    meat is to ours; that is to say, it contains the prott(id or nitrogen-
    containing ingredient of the food which is necessary to the sup-
    port of any animal, and also substances comparable with fat, called
    in general hydrocarbons. The nectar and honey consist principally
    of grape sugar, fruit sugar, and cane sugar, which belong to the class
    of chemical substances known as carbohydrates.. Now, all of these
    foodstuffs, except the grape and fruit sugars, have to be changed
    chemically by the digestive process before they can be absorbed into
    the blood. The pollen, which contains the proteids and hydrocarbons
    of the food, is taken directly into the mouth by means of the man-
    dibles and apparently is not digested until it reaches the small in-
    testine, and therefore it would seem that it is the cane sugar which
    must be affected by the saliva. The change, or inversion, as it is
    called, of cane sugar, which has a very large molecule (CHO1),
    consists of its reduction to grape and fruit sugars which have smaller
    molecules (C6H1,0O). Starch (C6HoO) must also be reduced to
    simpler and more soluble compounds before it is capable of absorp-
    tion. Its inversion is effected in us partly by the saliva, but starch
    appears to form a very inconsiderable element in the bee's diet.




    The alimentary canal is a tube which extends through the entire
    length of the body and, on account of being more or less coiled, it is
    generally considerably longer than the length of the body in insects.
    It hlias no openings of any sort into the body cavity. The internal
    organs-, are packed closely about it, and the interstices are filled with
    the blood, there being no special arteries or veins in insects. The
    amount of space occupied by the alimentary canal varies according to
    the amount of food it contains, and for this reason it seldom looks
    exactly alike in any two individuals examined.
    The part of the canal immediately following the mouth forms an
    enlargement (fig. 42, Pliy) called the phJiry,,i'. Succeeding this is
    a slender tube which leaves the head by the foramen magnum above
    the small transverse tentorial bar and traverses the entire length
    of the thorax. This is the e'sophaqus (a'E). In the anterior part of
    the abdomen the ,esophagus expands into a large thin-walled sac
    which is ordinarily called the crop or ingiluics. but which, in the
    bee, is known as the honey stomach (HS). Behind this is a short,
    narrow, necklike division, with rigid walls constituting the pr-o-
    ,'e1,tr't/uI,. (P,'(nt). Then cones a large U-shaped part, with thick,
    spongy-looking walls containing numerous annuilarl constrictions.
    This is the ,c, r.iclus (Vent), or stomach, of the lbee, frequently re-
    ferred to as the chylee stomach." Following the ventriculus is a
    short, narrTow, coiled ,mn(1ll hbi tc.tie (Sit) having a circle of about
    one hundred long, greatly coiled, blind, threadlike tubes opening into
    its anterior end. These latter are called the latlp}g'/hin i tubiles
    (.Jfal). Functionally they do not belong to tlhe digestive tract, since
    they a:re excretory organs, corresponding with the nephridia of other
    invertebrates and with the kidneys of vertel)rates. Following the
    small intestine is the large i/tc.411C,, or nc.t /, (Rc(-t). which i. often
    distended by its contents into a great sac occl1)ying a large part of
    the albdomiiinal cav'ity. Six whitish b ands on its anterior end are
    called the rec(.f1 glands (RG1). The rectum opens to the exterior
    through tlhe anus, which is situated, as already described, at the end of
    tlhe rudim ienfiary tenth of last segment of the abdomen (fig. 41, .A1).
    After this brief general survey of the parts of the alimentary
    :canal, we shall proceed with tlie description of each in detail, and at
    tli, sal;me( tie(1 gi' whlaxt is known of tlhe role each plays in tlihe
    process o ,f dige stion. What is known, however, about digestionn in
    the beel, or in any iiset t, foir tlNat aile'r, really almlo1nlits to nmiothling,
    but the views of various writers on thew sii)bject must be discussed
    briefly, in order to show how little lhas actually been demonstrated.
    The''l pharynx (figs. 11 B, 19, and 42. I/,/) lies in tlhe anterior part
    of tih' 1'iad co1,se ,ehid tlie (clypelis, exte(liding froiu the mouth
    t- 10



    dorsally to above the antennae, vlwhere it turn-, posteriorly and con-
    tracts into the much narrower <'sophJiagus (CE). Attac(lId to its
    walls are numerous suspeis(o)rial muscles, whoe(C contraction Iil-t
    expand the pharyngeal cavity, while the latter may he :ontraicted
    by the sheet of muscles -iirrounding its walls. In this waiy t1w
    pharynx is undoubtedly able to perform a sucking action, by IHii"n
    of which the liquid foods are taken into the mouth. Its latnral
    walls are strengthened by two long, chitinous rods (figs. 11 B and
    19, h), which arise from a median anterior plate in its floor (fig. 19, ,s).
    The anterior end of this plate is prolonged into two free, taperiing
    lobes which hang down over the lower rim of the mouth. The plate,
    in the worker, and the bases of the rods are shown in ventral 'view,
    removed from the pharyngeal wall, in figure 43 D. N(ear where the
    rods join the plate are (\vo long, chitinous pockets (mm), opening
    above, which receive the ducts of the two large glands (1GI) lying
    within the anterior part of the head. Between these two pockets is a
    transverse row of cells (4Gl), which have been described by Bordas
    (1895) as the sublingual glands," but this name is not appropriate
    in il.sects, for, while the gland in question may be suiggestive of the
    sublingual salivary gland of vertebrates, it does not lie beneath the
    tongue or lingua of the bee. Although the pharyngeal plate lies
    upon the floor of the true mouth, it is not, as already explained (p.
    44), the equivalent of what is properly called the tongue, lingua, or
    hypopharynx in other insects-this organ being abh-ent in most
    Hymenoptera. The only suggestion the writer can make, however,
    is to call this group of cells the venjtral or median rcn tral pharyngeal
    gland in distinction to the large lateral glands. A comparative view
    of the pharyngeal plate and its accessory parts in the drone is given
    in figure 43 E. The plate itself (s) is shorter than in the worker,
    and its anterior lobes are smaller. The lateral glands and their
    receptacula are entirely absent, but the median glands (4Gl) are
    much larger than those of the worker. Bordas says that each acinus
    of the latter glands in both the worker and the drone is provided
    with a fine, sinuous canaliculus, and that these tiny ducts open
    separately in two bundles on the lateral parts of the pharyngeal
    plate. The lateral glands are present in the queen, but are v'ery ,1nall
    and rudimentary.
    Especial interest attaches to the large lateral pharyngeal glands of
    the worker (System No. 1 of Cheshire, the supra(creCbral glands
    of Bordas), because they are regarded by many as the source of the
    brood food and the so-called royal jelly," which is fed to the larve
    'and to the adult queens and drones by the workers. Each consists
    of a long coiled string of small ovate follicles attached to one median
    duct (fig. 43 A) and the two are intricately packed into the anterior
    and upper parts of the head (figs. 10 A, 19, and 42, IGi). Each



    acinus consists of a solid mass of several small cells, which are pene-
    trated by a large ninmber of fine, chitinous ducts, arising in the neck
    of the acinus from the common duct of the gland. These follicular
    ducts can be very clearly shown by treating a part of the gland with
    weak caustic 1)otash. which dissolves the protoplasm of the cells
    and brings out the bunch of dtictules very clearly.
    The fact that these glands are entirely absent in the drone and at
    best rudimentary in the queen shows that they must in some way be
    connected with the special functions of the worker. Schiemenz (1883)
    and Cheshire (1886) have shown that their development in the dif-
    ferent species of b)ees is in proportion to the social specialization.
    They vary from a group of cells opening by separate duicts upon the
    pharyngeal plate to the highly developed condition they l)present in
    the honey bee. The writer questions, however, whether these authors
    did not mistake the median pharyngeal glands of these lower genera
    of bees for rudimentary represeItatives of the lateral glands. Bordas
    states that the former occur in all Hymenoptera, but Schiemenz and
    Cheshire did not seem to recognize them. The bumblebees (Bomnbus)
    have them almost as well developed as the hloney bee (Apis), espe-
    cially tlhe large females. In the genus PsyfIthi ,.i they are similar to
    those of Bowmm., but are smaller', while in such genera as Aindrena
    and Aithophora they are rudinenltary or consist of a few scattered
    cells. Both Schiemenz and Cheshire have thus argued strongly that
    these glands of the phaN;ynix are the organs that prl)od(llce the brood
    food. On the other hand, Schliinfeld (18S;) has made an equally
    strong plea in favor of the ventricuilus as the producer of this impor-
    tant material. He believe-; that tlhe brood food. especially royal
    jelly, is. regurg-itated chyle. Both Schniifeld and Cook (1904) fed
    bees in a hive some honey containing powdered charcoal and later
    found this in the brood1 food in the comb cells, thus apparently con-
    finiiing its ventrictilar origin. However, the charcoal that got into
    the cells might have come from the mouth, the s)oplhagu.s, or the
    lholey stoioach. It, of course. could not have gone through the
    stoiiach walls and entered the parviiyngeal glands, as prl))oved by Dr.
    J. A. Nel.,(. of thi, Bureaiiu ftroni microtome sections of bees fed on
    lainplbl;ck. The argtmiient.s. then, in favor of tlie stomach and tlhe
    pli;iryN-ge;ll glands seeiml equally strong, a:1d perlIaps the truthl is, as
    O(c(c'*rs i so maiy ..uch ('a.-es, that bo )t sides are right-that thle brood
    food i. a ,ixJture of clyle fromin the stomach and of secretion from
    tlit plinrii"geil gla; ds.
    Ariiliai't (1906) .eens to adp)( IHe )position that thle brood food
    is clyl. whi'ci lns 1a been acidified 1)by tlie addition of an acid from the
    g l;1nd.. Hie .tes., that the avid reaction of tlhe royal jelly is duie to
    liet presce' of tiiree- f)ourths of 1 per cent of tartaric acid. The
    contents of the ventriculus, on the other hand, and for that matter



    of all the parts of the alimientary c.;il:. are alka;lillne. IIell', it
    seems very logical to suppose that if thle I)r(o(,d foo(1 co(l-, fron m the
    stomach, its acid coiistituent is furniished by the glands in the h,;id.
    But tiet. difference between the broo(l food f)oulld in thle cell anId tl]e
    contents of the ventriculus is so that it, would .semi,, :is if a vry
    substantial addition of something more than a mere piti.Irvalive acid
    must be made to the latter.
    The brood food given to the queen larva., knowNvi as royal jelly, is a
    gumy paste of a miilky-white color wiheji fre-li, lbut whell taken out
    of tlhe cell it soon acquire, a darker tone with a yellowih-h tint. Under
    the imlicroscope it appears to be a homogeneous, very minutely granu-
    Ilar mass. It is very acri(1 and 1)puge1nt to the taste, and must be
    strongly acid. Samples examllinied by the writer taken from cells
    containinlg queen larva,' two and four days old contained a number of
    fresh undige4ted pollen grai n but no bits of hairs such as occur in
    the stomach.
    The possible ventricular origin of a part of the brood food and its
    regurgitation will be further discu --ed when we treat of the stomach
    (page 98). The writer does not advocate any personal view regard-
    ing the origin of this larval food-the fact is, there is not enough
    known about it to enable one to formulate any opinion worth while.
    We know only that the whitish paste come., out of the mouths of the
    workers, but we know nothing of where it is made or of how it is
    made. Hence we can but await the evidence of further investigation.
    The brood food is fed to the larva' by the workers and is produced
    in greatest abundance by the younger individuals. The larva of the
    queens are said to receive nothing but pure royal jelly throughout
    their entire developmental period, while the larva' of the drones and
    the workers are given the pure product only during the first three
    days of their life. From the beginning of the fourth day on, honey
    is said to be mixed with the diet of the drones and workers and, in
    the case of the former, undigested pollen also. Moreover, the adult
    queens and the drones receive a certain amount of prepared food
    throughout their lives; if they do not get it they become weak. While
    they can feed themselves with honey they apparently can not eat
    pollen, and consequently are not able to obtain the proteid element of
    diet unless fed this in a predigested condition by the workers. Dur-
    ing egg-laying activity the queen especially demands this food, and
    by furnishing or withholding it the workers prol ably have the power
    of stimulating or inhibiting her production of eggs. Arnhart (1906)
    says that the workers feed it to weak or starved meuibers of their own
    class, the material being accumulated upon the upper surface of the
    mientum of one bee whence it is sucked up through the probo-cis by
    the other. All of these statements, however, concerning the feeding
    of the brood and the differences in the diet need to be verified. They


    are based chiefly on the work of Planta, published in 1888. Cheshire
    (lSs;) :-t;ites that the stomachs of queens contain a substance which
    is microS.copically indistinguishable from the so-called royal jelly,"
    :(-ca(rcely a pollen grain being discoverable in it. If this is so, if would
    .-eelll to prove that the queen is fed this substance by the worker, for
    the stomach of the latter is invariably filled with a dark-brown slime
    containing a vary-
    CE| CE Iing amount of pol-
    len and in no way
    /resembling royal
    jelly. Cheshire
    Hr---S further says that
    1f -HS before impregna-
    tion the stomachs
    of the queens al-
    .Pvent w.ays contain pol-
    __ len, the royal jelly
    .--e--, S vent being found in
    ... -r .-7 them two or three
    A 4k.
    .I.._ ---days after impreg-
    Vent -- nation, when all
    traces of pollen
    tIc : "* --,- Ihave disappeared.
    -/*' ..., .*/I T h e n a r r o w
    S-HS esophagus (fig. 42,
    '".:, A ') ( is a simple tube
    .Pventr with a thick chiti-
    IiI'd /nous lining and
    4 muscular walls.
    \fe-. ^ iThe epitlheliumn (fig.
    Ve nt. -- / J"/, 5 srli
    Vent <45 is verv rudi-
    l'mentary, its cell
    C --- -D *- '< boundaries being
    rF-in. 44.-A, lioney stomach (f.,'i of worker with poIsi'rior end lost and its nuclei
    of ,(s..,,|i ,lii, s < (MF), pro.vintriciilis (Prenit), .i.,d interiorr ( appearing as
    nrid of ventricuilus (Vcni ); B, same of (it.t'vii; C, Ihon y ( )I ( |J (II g l fllt
    stomach (H.,1) of worth i1,slyIv rut ..awviy exposing the if imbedded in the
    stomnach-mouth (/In) of I'rotnrirculii. (i'rcnti) Iheiding into low ia. lovers of the
    vntriwuluus (Vent) ; D), hoiiny stomach of dronc'.
    thick transparent
    intli ; (Ilt). 'l'ie muscles are disposed in an outer layer of trans-
    V\Ir,( filers (Ti/clI) and an inner layer of longittudimnal ones (L.Jll).
    The honey stomach (fig. 4-2, IIS) is simply ai clilargemenit of the
    (sttfri(r 'end o()f thle (psopligilus lying within the anterior part of
    the fi bdomliinal c'avity'. It is 1vst dlevelopl)ed in tie workAler (lig. 44 A),
    kit is l)prtsvJt :dl-, ii llIn liit'('I (B) anmd in the drone (D)). The
    org:,iI should ple'rli'ips limv'e I)e.\ named the. nectar stomach, for its


    principal function in the bee is to hold thle nectar as, it i.s olleletdI
    from tihe flowers and to allow thle worker to a.ccumulate a colsidl,.r-
    able (Iuantity of this liquid before g oinig ,:u,'k to the hive. ll.I'IeIe,
    since the honey stomach is a s:,, with very distens!ible walls, its
    apparent size N'i ries greatly. When empty it is a i;mall flabby 1),ouch,
    but when full it is an enormous, bhallooll-shaped ba igr with tliin telse
    walls. The histological structure of thie honey stoilmch (fig. 45, IS')
    is exactly the -sanme as that of the ,'sophagii,. The nmiillnerols highl
    folds into which its epithelium (Epth) is thrown per tiit the e(lor-
    mous expansion of which the sac- is capable. Whlie1 a wokler with
    its honey stomach filled with nectar reaches the hive, the nectar is
    either stored directly in a cell or is given up fir-t to s.ome other
    worker, who places it in a cell.
    It would appear that all the food swallowed by a bee must go first
    into) the honey stomach, and since the bee's diet consists of pollen and
    honey as well as nectar, one would suppose that in regurgitating the
    latter the bee would also disgorge the pollen it might have recently
    eaten. Honey which is made from the regurgitated nectar does
    ild(leed contain some pollen, but most of the pollen eaten by the bee
    is undoubtedly retained in the stomach as food. The apparatus by
    means of which the pollen is supposed to be separated from the nec-
    tar belongs to the following division of the alimentary canal, but it
    is not known that the worker takes nectar, and pollen for food, into
    its honey stomach at the same time.
    The proventriculus (figs. 42 and 44, Pvent) forms the necklike stalk
    between the honey stomach (HS) and the true stomach or ventricu-
    lus (J'cnf), but a very important part of it also projects up into the
    honey stomach (fig. 44 C). If the honey stomach be slit open, a
    short, thick, cylindrical object will be seen invaginated into its pos-
    terior end and having an X-shaped opening at its summit (fig. 44 C,
    nnn). This opening is the mouth of the proventriculus, and its four
    triangular lips, which are thick and strong, mark four longitudinal
    ridges of the proventricular tube. This structure is commonly known
    as tlhe stomach-mouth and is suppos-ed to be anl appar iatus de-
    signed especially to enable the worker to pick out pollen grains from
    the honey stomach and swallow them on down into the truite stomach
    or ventriculus, while the nectar is left to be stored in the hive.
    Cheshire says: "While the little gatherer is flying from flower to
    flower her stomach-mouth is busy separating pollen from nectar."
    This notion is so prevalent among bee writers in general that it
    passes for a known truth. Yet it has really never been shown that
    the worker eats pollen while she is gathering nectar. Probably no
    more pollen is ever mixed with the nectar in the honey stomach than
    is found in the honey itself. Furthermore, under normal conditions
    pollen never accumulates in the honey stomach, even when the bee



    i-, not collecting nectar-or, at least, the writer has not observed it--
    while, finally, both the proventriculus and its mouth are just as well
    developed inl the queens and drones as in the workers, though neither
    of the former are known to eat pollen, and they certainly do not
    gatlur nectar.
    If the honey stomach be cut open in a freshly killed bee, the
    provelntricular mouth may be seen still in action. The four lips
    :pa:-miodically open wide apart with a quivering motion and then
    tightly roll together and sink into the end of the proventriciular
    luilmen. This. of course, suggests their picking pollen out of the
    niectar, but it is probably simply the ordinary process by means of
    which tlhe provelntriculus passes any of the food in the honey stomach
    on to the ventriculus. Nearly all insects have some such proventricu-
    lar apparatus, which simply takes the stored food from the crop as
    it is needed by the stomach. In some insects it forms apparently a
    straining apparatus, which prevents coarse, indigestible fragments
    from entering the stomach, while in some the proventriculus may be
    a trituratillg organ comparable with a bird's gizzard. Bees, how-
    ever, do not crush the pollen either in their mandibles or in the
    prov'entriculu-, for it occurs in perfect condition in the ventriculus.
    Hence, before the current notion that the stomach-mouth is
    for tlhe special purpose of taking pollen out of the nectar in the
    honey sto)lmach can ble accepted it must be first demonstrated that
    the workers eat pollen while the honey stomach contains nectar to
    be stored in tfhe cells, i. e., any more than is disgorged along with
    the nectar; and, secondly, a reason must be shown why the queens
    a1d(l droiles should have a stomach-mouth as well developed as
    that of the worker. In the meantime it appears most logical to
    Iregaiard the proxentricular mouth as simply the ordinary apparatus,
    possesSed b, insects in general, by means of which all of the food is
    passed froil tihe crop to the stomach.
    A lonpgitudinal section through the honey stomach, the proventric-
    ulni and the anterior end of the ventriculus is shown in figure 45,
    which is made from a queen. The proventriculus does not differ from
    that of a worker, but the honey stomach is smaller and not so much
    turned to one side (cf. fig. 44 A and B). Tile two muscle layers of
    tile ,plagiip continue downN over the walls of the honey stomach
    (T.Vlcl and L.11cl). The outer layer of transverse fibers, however,
    'e,:-Ies at the postertior end of this organ, while the longitudinal fibers
    (10i tti ltie poteri'orly over t lie prevent ricill us and thle ventriculus as
    an external lnyyer (L/r). A new layer of internal transverse fibers
    b (gis til th pJ )r\(veit ricular walls and extends backlward on the
    ve'ntirici lIiis (T.f[.1) Ibinc,'th the logiidtudinals. Hence the muscles
    on' the proc1,Vitricuil is and ventriculus. The proventriculus is deeply in-



    vaginated into the posterior end of the honey stomach. Each lube
    of its mouth forms a thick triangidlar ridge< onl t walls of its
    lumen, in which lies a special ma- of loiigitudlimil muscle filwrs
    (LMcl). The epithelium of the lumen is lined by Na thick. smooth,
    chitinous intima (Int), while the lobe, of the mouth (un) arc pro-
    vided with bristles point-
    ing inward and backward CE
    into the mouth opening. ., ,
    The posterior opening .
    of the proventriculus into.p --LMcl
    the ventriculus is guarded I ---TMi c
    by a long tubular fold kt-- .
    of its epithelium (fig. 45, Nu-- r
    PventVlv), the pro rent ric- -
    Wdar v'lve. This would HS
    appear to constitute an |fF ---LMcJ
    effective check against the Ilnr ... |-,-E
    escape of any food back ~-... T--P
    into the proventriculus. It .
    looks like one of those traps ,'
    which induces an animal to Pvent : Tii
    enter by a tapering funnel ."TNU
    but whose exit is so small Epth
    that the captive can not
    find it from the other side. Vent L-McI
    Yet Sch6nfeld has elab-
    orately described experi- "
    ments by means of which A
    he induced the ventriculus k. > >. .TMcI
    to discharge its contents :-- ''
    through the proventriculus tyi -2.
    into the honey stomach and
    even into the end of the Pjn t Vv
    oesophagus. He says that '
    he did this by gently tap- Eh PP
    ping on the honey stomach FIG,. 45.-Longitudinal median section of base of
    and the ventriculus at the esophagus ((E),honey stomach (HS),provqntricu-
    same time. The experiment lus (Pvent) and ventriculus (Vent) of a queen.
    was repeated many times with unvarying results and Schonfeld de-
    scribes so minutely what happened that we can not disbelieve his
    statements. From these experiments he argues that the larval food-
    stuff is prepared in the stomach and regurgitated through the proven-
    triculus directly into the esophagus by a contraction of the honey
    stomach which brings the stomach-mouth against the base of the wsoph-
    22181-No. 18-10--7



    agus. We shall have to postpone a further discussion of this subject
    to page 99, after the ventriculus and its contents have been described. '
    The ventriculus (fig. 42, Vent) is the largest part of the alimentary i
    canal in the bee and is bent into a U-shaped loop of which the pos- *
    terior arm is dorsal. It is cylindrical and does not vary so much in
    shape and diameter according to its contents as do the other parts of
    the canal, although the numerous transverse constrictions which give
    it a segmented appearance are not at all constant. When examined
    under alcohol the ventriculus has an opaque whitish appearance, but
    in the natural condition-that is, as seen when examined in a freshly
    killed or asphyxiated bee-it is of a dark-brown color with lighter
    rings corresponding to the constrictions. The latter represent in-
    ternal folds where the walls are really thicker than elsewhere, the
    color being due to the contents which naturally show more plainly
    through the thin parts.
    The contents of the ventriculus invariably consist of a dark brown
    mucilaginous slime and generally also of a varying amount of pollen.
    The latter is most abundant in the posterior arm of the ventricular
    loop and is often densely packed in its rear extremity, while the an-
    terior arm may be almost entirely free from it. The pollen in the
    veintriculus is always fresh-looking, the native color showing dis-
    tilctly through the enveloping slime while most of the grains yet re-
    taill all of their contents. The writer has examined many samples
    of pollen from the stomachs of workers and, in all, the great mass of
    it showed no evidence of digestion, the color being fresh and the
    contents perfect---onmly a few had the latter shrunken and seldom was
    an empty shell observed. On the other hand, the pollen contained
    in the small intestine lias invariably lost its bright color, the contents
    of the majority of the grains are more or less shrunken, while a num-
    ber of empty shells are to be found. That in the rectum, finally, con-
    sists in large part of empty shells or of grains having the contents
    greatly shriunklen and apparently mostly dissolved out, although a
    few perfect and bright-colored grains are always present, looking as
    if entirely unaffected by the digestive liquids. From these observa-
    iiols the writer would ('coiiclud(le that the digestion of pollen takes
    place pri1icipally in the inttestin,. In all parts of the alimentary
    tract there occur numerous bits of feathered bee-hairs, but these seem
    to be especially numerous s in the ventriculus.
    We are now in ia )position to discuss the possibility of the production
    of the brood food in the stomach. Schiinfeld (1886), as has already
    beeni stated, -jrgiies t hat this substance is regurgitated chylee from
    the 'venttricilwli.. Arnha.'t (19O0) adopts this view and elaborates
    (i0I.sid(enraly ul)pon the chemical process by means of which the trans-
    foria tion of chyle into this larval food is effected through the
    addition of tartaric acid from the pharyngeal glands of the head.