Mutative reversions in cotton

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Title:
Mutative reversions in cotton
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Book
Creator:
Cook, O. F ( Orator Fuller ), 1867-1949
United States -- Bureau of Plant Industry
Publisher:
G.P.O. ( Washington, D.C )
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All applicable rights reserved by the source institution and holding location.
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aleph - 29630086
oclc - 40727532
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AA00020807:00001

Table of Contents
    Front Cover
        Page 1
        Page 2
    Introduction
        Page 3
    Reversions similar to mutations
        Page 4
        Page 5
    Relation of reversion to coherence of characters
        Page 6
        Page 7
    The Hindi cotton considered as a reversion
        Page 8
        Page 9
    Contrasted characters of cotton reversions
        Page 10
    Reversion implies continued transmission
        Page 11
    Reversion interfere with Mendelian expression of characters
        Page 12
        Page 13
    Reversions of later generations of hybrids
        Page 14
        Page 15
    Agricultural significance of reversions
        Page 16
    Conclusions
        Page 17
        Page 18
    Back Cover
        Page 19
        Page 20
Full Text
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U. S. DEPARTMENT OF l\( t .I. II'lE
BU'RIE.% l tiF PI.. NT IN I 'I I .- 'r .il.ir \. .
II I ,, \1.1I A li i Ii-, f r .1 llinr.,-,





MjrJATIVEI'rlljl, REVIlSIoNS IJ (j 1l Or<.\






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FF
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N1V 'rEP PT
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SSDEPOSITOR


*m-i^-.,Ti ~ r --.'t~-F Tr r ''r1:f 1




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BUREAU OF PLANT INDUSTRY.




7i1" /if B urQu. OEtE Fr. IV T. GALLOW. i
.4'slatta t Chir/nj Biruill, ';. II \R(IL1[ I'=WELL.
.Edl.,,. J E. 1," hWEIL.
Chief Ci rk. J.%111F.-; E. I'-% i:


[C ir. 53]










11 I' I -'.;I

1MI"ATIVI RF RSIONS IN\ C()TI()N\.


INTRODUCTION.

It is ras'inni vil fur \vIitrs on liririlil l iihrdili.w 1"1 look Ipiui
I'v", l iti ll'i, ;111d liiil nl ll ll,, ", ...- I- 'l l'r iLIIL ,'x '.p l ,,i l ilir'l i l 'i ,i l lt
IllIllI I't i iL'iZllI1 ilI14 ,f OLt. l i I'u li pla tll tr,' iif fri'li'nt ii,,l ri .lrE
Miro l iiittnv iif Il1 ,. 1,,11 ,,r ,it ,III I I. l \ rv,.r in-. I.\ m ',l,_(,. f i, niv l ,rr ,
eX ten t 1lll1l u -,. f [I" f ...r.n l %'%,,,'I,. S I +l l llI,',o \Vh ll,.'rlil 1ll[), ll Il ,lill
prbd i'iiis 4', lr, irmi uinll :,a])I.,11 i 111 ,f l .ri,' ii'-. f.r '.,,i.ii In-i f
this kili, Iip|,'l i' t, Il' l u ,f I ll,' t'lihi f Fi t'r+',,- of vi'i'iiirii, n 1i, i.
M nl iV p ilimil i r. ,l V.1 c .. iriti, in- r 1111 '4 ir ic (r|, I ll ( t 0 11- .,'14 l' ,,If livl i'il-
izatiim ) alln fi ll,,l,., tl,, ,li\ ,'r-iti,..-. iirl'+ -..l 1\ 11111 c1-l l i, i-. lln, l-
V'idUil vitriallituil.i ihuiih I pI r: I,.r ti ,hii're frluiu tl ]l)jiii tl -',t'k liv ;L
singlh, f altl ure. 1)2ll i-I111I .ll -.]uiw) IlInI',,i,-. j .ii. li.ir t" i;ti;i,,rI. -tlic-
OutSidtO -f i llr' oiili tii \" rV l ,if \ tri.A inin ,,f tll,' I.I,',I' il., lYpl ''.
T lih ctitt inl, I I ll) Ii' I L Iin f -I-iltll It-l'; )1),l l p, 111111 \ furI' I lit-,
obst'rvation t ,f suli facts l catl-.", i N .O-, lAll f Of i it lls ;ilr r'.,liiV
sePn i II Id (III[)iLr,'tl.
(C'lhangi's (if ," li r iit'I'rlS Art' iiw tii' ii'iI'. l to ti ks k. it llt it In iV' I11,,1
recently h~ly liiiLi/-nl. Ev'ii tin llr i,..t imii i, i vn ii,.'. .. ,li ivs
the Triunm ph I'l hin ci,,tt, ii ,ii o 'f .' ,-.. iIILiyV iliIli Iii.I l l.,in ., fiLY,
shOlw siltl 14n tb-litl''irtIT 's frlili tll' Iii 'r iil cli-;ii( tlr- 'f lli,' \:L iil ,'
CS t't'ia ill i" \ tlI'n tit i ii iii Li ll'S a Ii new1 [ II i l 'ri '. Tihe iItil lr'' ilf
Suclih vliriililtiIs iiiI tli- frl'ijiit'iiU 11 I li w lihili liv il'u( r Iiniu 1LIt
that tli,'" ri''pit's,'lI r'vt'vi-siiiIns tIi tI i, ii li,'r tliv', rsii i' f it lI i IVIhI lI1 tt
haiv%'e lb'vjl1 s ilpprn's.sr'l '>\ -wrlvvtli.ill."
Ht'virsi.i 1 ii niv In' lv ii, '1,I ,l. tliA r'I tl ni ,f ;tii 'I'slt il ,1 liitil. L IL'.S Ii
exprt'ssiil. lal liil-; ill' iLiiiiii.lll I ih tt tlitl.r frnm I liil iiliiniiliti' il liI -
tivres iln ShltM ill_' (tlilir,-LI.iIii.SliCs tf ilcllit'., ii cest -l ; 4l 1 il' lih'-,rrihn iI ;is
reve-sionsi iu- lli' \ -i- backs." Slripil pIIs, blac pigeIn is. nil t'ii' i', f I 'N 21n, iinil l.t ', l ii- lltl'I ii tll 0i h VIltii4; I li-t3 ilJii'lr
0'CILS'i liiLI V illn punr-bri-ul \\ lilte viri'eti, iie ; ll L hIboki'l u2j,,ii iLS
revi't,,si l-s lt,o iI chaltr cIv l1i i,-4 's ,if c, l4, ,w,. l iill v'tlr .-;. I vi,\% .iri,,I s
nIIv It 1 ,' rI't'kc llkii l is p li'i i 'l if ilit Variiinl iinuli Iil ils lIlriiiL iliu
iCx 'ss.iol olln ;i fi'%\v of Iltli l ii n tit'St l ]rci li i)rii ..1 i IW tilI illn liir
respt'cts tt' ill hilln l. ri, srin 1,, li, I. lPiD I i, l ii, lllr .l Ir- if Itl Iir ,.,I.
,i T '1il .AiljuIi. r'w *,i I ',liu i \'nri li''- IuIl 'tii ', I I I iir,.iui L1 A'l.i riT I i-tr ,
" S. Ilepi I" ..t: r i ltun I'H i i. -1ii
(Cir. 51






MUTATIVE REVERSIONS IN COTTON.


Reversions may be called total or complete when there are changes
of whole series of characters of parent varieties. 0
REVERSIONS SIMILAR TO MUTATIONS.
Whether wild species originate by sudden mutative variations or
not, there can be no doubt in the case of tlhe cotton plant that definite
variations occur and that they can give rise to new cultivated varieties.
The great majority of such variations are not preserved because they
are inferior to existing types. In a uniform, big-boiled type of cotton,
such as the Triumplh, many small-boiled individuals with different
habits of growth and other peculiarities may suddenly appear."
In dilute hybrid stocks of Egyptian cotton, with only a small pro-
portion of Upland or Hindi blood, individual plants of apparently
"pure" Upland or Ilindi cotton are found, while the other plants of
the same ancestry show only the usual Egyptian characters. If the
Egyptian parentage of these variations were not known it would not
be suspected from any of the characters that are brought into expres-
sion. If tlhe experiments had been conducted on a smaller scale
and onlyv the Upland or the Egyptian type had been familiar, these
changes of characters might have been looked upon as rare muta-
tions into new species, like those that occur in the garden variety of
the evening primrose studied by Professor De Vries in Holland.
It does not seem probable that the niutative changes of characters
that often occur in cultivated stocks of cotton represent the attain-
ment of new characters, for the characters that come into expression
in this way are commonly found among the more primitive types of
cotton. Even the characters that have received the largest amount
of selective improvement from breeders, such as large bolls and
long, strong lint, have been found to exist in equal or greater degree
in related types of cotton that have been cultivated only in tropical
America without any conscious methodical selection by the Indians.
The more degenerate vari, lions of the Upland cotton, with very
small hulls anti very short lint, are inferior to any of the varieties
cultivated in the United States, so that. they can not be looked upon
as results of crossing with other varieties, except as crossing may
be supposed to induce reversions. It is not necessary to suppose
that these inferior characters are new, for some of them are closely
paralleled among the very diverse forms shown by the Kekchi and
other primit ire U'pland types that have been introduced from tropical
America and acclimatized in the United States in the last few years.
Several of these newly introduced varieties also share the same
characters that render thle IHindi variations of the Egyptian cotton
so strikingly different front the typical Egyptian plants, such as the
Local Adjustment of Cotton Varieties. Bulletin 159, Bureau of Plant Industry,
U. S. Dept. of Agriculture, 1909, p 17.
[Cir. 53]







II' I % Il 'I Ilc'.VIIC.-',IhINS I N inl IIN.


shorter )lo ,4' of I ic iivr,. flit iel ir I '.n rrrI'' li *>lr, W ,iiil I lie lililii.ir
texItl 'ir TI o otr tlir- r n f vll, ,'.il\ 11,11,.. -I- 1iiir I 14ii 1 11ll,]n .111b
usual -v ll 'rtw n ,tnt irnlt, .) lanuil Ih l ?,h Iti 1i i l,. ji"" iiliiiit, v prt-\i'..iiI,-l
o'lervei onlyv iiioim.I tilt' (ciilitil .\Air1 jill rolled li. MIl. R,,,I.,idl
M M eadtle has foLuiii Ilint llt II *' I" ii i %.II \ ,Itl Vi I" lit 1111111 iii, i,,1
tire Sme)metillesI tIlirt''-tiitlh li. l.-, a;li). i 'I iil III l 1:1l>'ll ./Ill t ,'ii.
i pert'ennl iail Iplh nl tI tly fXmiiii 'sl i II ( ill tiL lniii i \t ii i l',i-'.. ,,: ',%l.
E, v[)timni-like holl-k T hei I, lls oI l tllit I I ,l ,,, ii ,,i, li.i\, .1 ,, i,,, 1,, .l1
CUlom e folrlm l and !lhrll[tly Il v ',inl;nl,'. T IIe '.,,nl'.. ,, 11v.. 1 ,li .,11d
even, w ith e ,il ]l l l- t '],l\ lnir, 1 il l 111n t l i .-I., . I.lnlI liTr I' il,.r i \
. imht~ l'Pt] w~illL v',t i't'l' l ,If Ill( (' i Ii ll k. ll A I fI ;III I l l|, ,l r ,,i,- '
The agre''iment o(if lt' Ilt i \i ntl i lie ( *itr'l \%la Hi'iiier iin' t.l ,ir
cotton extends even lto thile frequent i-lh I'] ,I I 4 .) ,, ', 4 fiol i, :,.
anion iifnnteclii lized i l 1l1int,. Ml lli Il|t's .il l C, hluxurianl sterile, orn" lnitv-ln1ii 'il i 'ill' l0l;-ills M 111 ,lhl i lr l.% ,l.',IIIIIIIIh d
five-hluln t uinLt % 'St-V .n-l' ll-i| IhIVt'-. S i. hlliM a; iiil 1iiin,<' fri i. lni- |l.n lls
have (he le VVts n110 ',1 llev'i l\ 111;1114,, \%I li l1 lir in'.i.'Ll 1lr,'1c ll.,W,
regularly tl 'lode 'tiiel. Ver\ \ vi,,riiili-, 1 h ,ili-lika' plIiits. 'ifli ii li.i\.
the same gene'rill apii|pt'iraince' i1 E',.]yIiri-l'|l hIl lii lIriil- anal li.i%
r' 1)resent liv ritls t0t'l en w t hel Iit' 1 \.,.vll ilt t ,114)11 .,nll 1li E\ cm 1ir111
forini tf the Iliinli. lit'h liar. -Ij/.. r u. I, I l' a ii iti i'll % I\\ ili nlr f-,i4'
that characters of hotili of I l i lirl-lt ty[pt'- ,IrF hllro litZlilt I .\-
pres-sionl. N4o tendfiK-Y 4 to iiiii mi;! liiXiiri.in c iiii'1 n '(1i
L' anlh I li vbritds tltul Sihow tli a Ii;ii;iiilr- ,f inilv" ,V it' ,,f l( li t l p I.r iI
types. 'IThiie un unusual vigi r 2t,)pjiLl -. tIl li, liI -.iiiit.il ;I)lnliit, ',ili,
in some WilV ronnected \lti lie tc'll-ii l ,iit, colirt inI le, E'.\Jln--InIl
of tile tlivergernt t'iziir' ttl I 'litllheir thll ;i a colisa< 'lelile of -ttvri]ilx.
The abihnornial viegtt iVt 'ivgitr il' Iii- l- lx' iiiuntiuife-;ttcll in lit' 4'u'li-'r
stages ,of growll, before illiv f fli' llslits hlavt' leiithiIl It';i'lli.'. .itze.
Tile close siniilirit s a l f if tile v';llint fa-1lll l f Ir li t i nluilin iifi'reili
kinds of cotton nim ie tllkeln t,) indtlitaIe 1 ml un'.cPst rl,] liiti-icttoerlisticts
are returning to exPression. Otherwise it \woill niced to1 Ie ;ibe.injiild
that the many different kinds of t'cotton aIre eln mged inl tile frniit ionl
of closely parallel scriPe.s of new species. Vhetlher the cotton v+i'ii,-
tions be looked upon at s intltitin.ins or njot. it is eq(tally ,desizziit, to
recognize their rehlition tl reversions. It iniglht be us proper Ilo :Il|
them revertive inutltions its mu litii\e 'revers'ions, except tht lh lie
idea of reversion is older and bette r .estahl liShed (uI n fithlt f nIli\
species or new characters originating 1bY mutation.
The range of ancestral diversities lmint aniv he expected ti renippear
in reversions must lie learned bY the study of the wild r.nitivves if
S"Origin of the Iinii oittinn tirti-ul.ir 4-2. iurieati I.i PliantI Inhi.ti r ", I1,i1t
of Agriculture. 19q09.
b The Vecwcmuiv e V'ir f HFTyhribrid anit MnIrui. iiin- I'rik'edinIg li.L,,gifal $ 1, i \"
of Ws. hington, val 17, 190, pp SI. 'i.
feClir. 5i








6 MUTATIVE REVEHSIONS IN COTTON.

0111our domesticated plants. It is a mistake to think of natural species
as uniform groups of plants that show only one set of characters,
like our carefully selected varieties. Very few of our cultivated
plants have so many wild or unimproved relatives as does the cotton,
,to serve is .t bl:is (if jtigt ntent regarding ancestral diversities and
r(versions.
RELATION OF REVERSION TO COHERENCE OF CHARACTERS.
('miplete reversions may be considered as related to a phenomenon
already described is coherence of characters.a In cotton hybrids
there is a general tendene" for the characters derived from the same
ancest or to come into expression in groups or combinations. It sel-
doi, or never liappen,' that a single character of one ancestor comes
into, full explression in a hiylbrid; that is, without being accompanied
by the expression of other characters of tlie same parent. Coherence
of characters appears to have a physiological significance. Among
time hybrid plants that are superior to tlie parent stocks in vigor, fer-
tility, and (tiuality of lint, characters tif both f the parental types are
brought into expression in coherent groups. Hybrids that bring the
characters 4f only oine parent to full expression are not superior,
while those that show incongruous combinations of characters are
notably deficient in fertility. A notable example of this relation
app.iaredl in a field of Jannovitch cotton raised from imported seed at
Simertim, Ariz., in 1909. The plant had the habit of growth, leaves,
and bracts of the Egyptian cotton, but changed suddenly to Hindi
characters in tlie long-toothed calyx, white flowers, and broadly conic
light-green bolls. At the same time it retained the Egyptian charac-
ters of short stamens and long exerted stigmas. Though having
.reat vegetaItive vigor, this plahint was quite sterile. The anthers con-
tained pollen, but did not open to shed it. The stigmas were abun-
dantly cross-pollinatedi by insects, but no ovules developed and not,
a single boll matured.'
VARIATIONS OF DIVERSITY IN THE SAME STOCKS.
The fact that plants with a preponderance of Egyptian ancestry,
such as three-quarters or upward, may show little or no sign of Upland
admixture accords with the general tendency toward coherence in
,. Suippri-.'ed and Intensilie, I tCharactern. in (Cotton Hybrids. Bulletin 147, Bureau
of Plantt InduI-try, U S. Dept of A,2riculture, 1909, p. 16.
tb The empty ,.arpI ify this plant showed a further peculiarity not hitherto observed.
The ridge that marks the middle of the wall of the carpel, the line of dehiscenceofthe
ripe fruit, gave ri-_' t, a series of long slender hairs that projected into the cavity.
Hairs of the same kind were found afterwards in normal plants and may be looked
upon as an additional storm-proof character. sincee they undoubtedly help to hold the
limit nd ieedl, in place after the carpels have opened.
I f'i j. J


S








S 1M I I \ 11\1 ; I I:iVi'I' .Il N I I I -ll 'N.


thec rxpr'Ssiolm i i f ut m rlt i ii i'- 1l1t imiliri mi. tih firthy'r fi.r t int Im lI ill, ,I i ti.lp i Ini ,tl % I' \ ,_ I) I. Ii.tiI .inI i-I 'N
I11% lm d '}purt fi l lIra I'L", p inllii ,li~ir. -l rl i'rt.ll, ,t, i ,'-s -'-'l ,,'p ,1,i ii-
p hii' uV"i; i -Iv l'f lill l'|l;,: l ,r I lind I i.im ,...111.1 IIll'mi r ,'IN 'rl.-l,

u po(n the El' p tl rn i i li l,.l ,, I ,.,ilf-Il,,i,,I [I I l..iii l I lI,-r i. .riIi.i;,l
re hluctinn of l expri-r.. nill i ,f V'pi l.iiIl tlu.it rfiit'lic'- .,. I. r'iiiii|.irl-1I
Wi ithlli thie rro..ss.s f ,Iiill-Il ,Im i 'I I V I: ,iiml liiI, nlt i l1 I'L'\ I'jI i;-ii' 11ti ,,ii'ch
lilultioi ls doi iot prI'rliit l,' id m I' -i ti:- pi' 'I '|leht r I 'il diiitl f, iii, -
1'p iini il od i I lii l I iii 'ic] t i'- I .. I i.it i-itTi, I Iiii:mi,.l| l., il, it i %r it It. iiiI
ex p ressio n i\ Tn it rl,'I I' I; 1, 1i1.i% I'14.11, li li' [, 'lllrV"1, 11" 1 rri I' l
to x I pr h' i .xpl ',i l III I I II 1 ,iiir f Il li' 11 II'l )'l ,I- f I ll I ,1X.t *i'll'-ilr l I'll
(O llt e plilltintlg ll\ It litl i''l lilt.% ;I',\ : I ,i,, [ i li-i :l1 l T -r lill|;' l,-ir'e
to one parent, ;illOl li i Iiili ii r I lit, lil i p, .i i'lm )Ie H Il.lliiL'
of it Sto(k of 'r .l mli I lli ,lm \ Ili, lim.: .. If ,,f I .. I ,:i lll ." 4irVm ,,t ill-.
w'hiler iiiiothi.'4l.- | ilit iIIir I iif' l :li -'' k 'i i 1mc 1lr'i ;iim'ther p r! .f i if i- I'
s8 11li, t -li :i] \ ,l >\\ ,'1r\ |>i') iii, miii '\ 1 1 1,'-I '1li-,1, lTl.ltI"iitniL
of tlie .1iLtll(ovIil Ii \% ilri'l\ f ll-' -\I ll 1i.i, 0, i i t I 'lii i l119 I L, lI I lii1,1
i in i\vui lu ll t f Is .id ex iili, firill. L III l_'I, ,, I. l.ii i ,-. ,,f fll-, .i.in,,,
stock of seedl illn '1 )s .( ii \ ,'i m'r\ i lt.\ 1. 11i l ii i ; ii I I% ]Iii i lit
conipa trnttiv'lY -lii., t ''ih'ii in if I inlit Il ,'ii *ii :Ii'i \\ 'm'm I' l''t' ."'
A q question n -'i\" ll ic r.,i-,,l r1L' ,ir, ili' l v In' :iltl II-llIt-it \ -if tlii
extreme example' % lr.r i-irplvi Im\v'l,-ii0'- lt:i: -''reii n'l I, I.,1
plaii'e, ius it \vere, Iv wh im'lilc',i byAlltmmtL'I I lli'i i i1 I,'.i-,li I' ,i, lt
the equlli inxl m id 'il iifiriii v ,;i iiifril i iiij',rlil h',_. i) I.ilt c'h hl,
it is still l -.Ihl ie t iniiiIIlil i' t liiii ILO, i',l 1 1 ,l.iili'll ll \4i0- 'if ilif-
ferent origiln from i I ll gnri i it Il !ii)'i. ,' 4.1i IlibiL.'li ,l ll ii ;iii, fi ilii
the sarne iiporlired1l -lock. Si li I p -....ilmtili',- W ilie -iirkiili.' if I lire'
smooth H indli <,''tl 1f i, Ilim, Ii ll iii .f lif lii Oiw I.il I. l 'm .ri iiirir iil.,
or early dv itlih f ith Ili' limil .,mlltiii:,-, liair : il-," I, lil it k ,lMmimi % ilt.
though h t lie c.h illi.it. l l .in i li 1 a il4 ,m i . 1 ill, ;ii4-mrmh :ili\ ,v (11111'e14t,
explili tilI n ,m f i lite ta'.r ;ippj .ir vml' ri'lii mI i 'm ',im' m 'i'-i'-l iii 'liiir.il
belihavioir -if ithe Kgypulirin i iin i jl u t l il, li til, mrmint Ifihl- .iimil m'\j>iti-
m ental |l .ts ainld till ,.'lnl'ru il ,'Oiilt,-triii2 f llt, i dIi iiiliviclli.,Im ii
the pltl intiig s I>f I 'ii!) 'ivm I1tl -%iilp ,irt '1 fil ilhc e it litti lli' -in-eu "f.l
different. A in ib-ilu,,li, *>tmrrmintticm 'if hie inillter \vill r'(|iiire', l,'
study of more inili crmii- m;ldm -ill Iiir' pr piin int 'f -t'mI. nmiixd % ilhI
special tlioroiithnli,-- l"ii\ :v iil Iliv' .-iiili \ *f am lii I iti l- ,i i iii
of ianl m f tle clifTm'r ir il rli hilili,. tli iai I:;\ bi.' iyrimiumh .
Ileg lau r fielhl pinitilllig. rf H. .t tiiln -cit 1 t ii liiie liiicle Ilm erCiv'
the purposes of 'weli exl'\ riiii'nt'.. iut i t dl.i iiitll, tidt lutilpe nl ill
advance thle o|,lliterail v ilen.e filr explcliug tliit ,r1-\p,1 occur ind l thlalt tli t' ile likely into aippe r in lili'lTiit iiilith',i'-r :ill,
"A Stud' ni Divenif' in l-'.yizp .inrm i',,i,,i illlIt, in l'-,, Iiir.:i ..i I'l.int IJ iui-ulr:.,
U. S. Dept. of .Ag culture, I.SO,, lip IS-21
[CIT. 31








8 MUTATIVE REVERSIONS IN COTTON.

degrees in different plantings, even when t lie seed is of the same stock.
''lougli breeding is undoubtedly a very important factor in reducing
diversity, it is no less important to ascertain the relations of environ-
nent to the occurrence of reversions. Such differences of behavior
arc frequently shown by the reversions of the Upland cotton, andti the
11ii regular variations of the Egyptian cotton appear to be susceptible
to) suchli influences.
Other forms of reversions, both partial and complete, have shown
relitifon to differences of environment in experiments with cotton.
Ancestral characters that are prominent in one locality may be
entirely suppressed in another plale where some of the same lot of
see' I his been planted. Not only tlie amount or degree of reversion
but also tlie frequency with which particular characters are brought
into expression is subject to change through differences of external
conditions. The failure of any complete Hindi reversions to appear
in the Jannovitch planting of 1908 does not appear merely arbitrary
or accidental from t lie point of view of other experiments, but may be
connected with tlie facts that the seed was sown rather late and that
the plants developed tinder conditions of abundant moisture and heat
that have shown a very general tendency" to bring the extreme
Egyptian characters into expression. Grown under such conditions,
plants that are known to be I'pland hybrids usually take on the ;
,1replete Egy ptian form and show very few Upland characters-
somiletimes none at all."
THE HINDI COTTON CONSIDERED AS A REVERSION.
Young plants of the Egyptian cotton share the foliage characters of
the Hindi, including the reddening of the pulvinus, the wrinkled,
swollen cushion where thle veins meet, at the base of the leaf. If the
Egyptian plants are kept small and stunted by unfavorable conditions
thle resemblance to the Ilindi continues longer, so that plants that
finally develop with typical Egyptian characters may be mistaken for
Ilindi. Late in the season there is another partial approximation
of thle foliage characters, for the Hindi plants generally lose the red
color of the pulvinus that serves as one of the most conspicuous
diagnostic features of the Hindi at early maturity and during the
preceding stage of growth. The general colors of the leaves are also
less distinct ire in the latter part of the season, the Egyptian cotton
often appearing somewhat lighter andti some of the Hindi plants
becoming darker.
Plants that do not show very distinct Hindi features in their habits
of growth, leaves, bracts, flowers, or boils may still betray Hindi
a Suppressed and Intensified h'laracters in Coiton Hybrids. Bulletin 147, Bureau
of Plant Indu-try, U. S. Dept. f Agricultuire, 190!9, pp. 17-23.
(CUi. 53]


-<










Iill,...,,>I,,.,,. ir,, I . deep ly co e lint YT der I peta lsand spotI
liIn ,,', \\ II Ii i\ .I he r I h1 i tire froI I_, I. i t Ih t r S
!, ,.,' ,t,.ir r i.,11 ,n ,, i, 1 11 ,ited ++s+ evide~nce +,f the lpresend'm+ of HlindiI
l l.l r ii. -. i't 'l I n l ,' i "i 'i. lft'3 h l I1-i 13 I .|.. ..' thliat : l*.,,l u tI 13 +3 slht
ItItIt r'!,;,n ;,'t,' ,11 ,,.,i" '... u l,, ,i it 141'x 33l3l s 113i3' f ++lil)t14'333 i ll t
11 itu n :i"\ ii '" i i l:,t i. ,n ,i t ie l U -II i ll-Nhll h l 3i't'l +tIher itlf' riorru 333c31' iii 3
11 13l II,'ir:,, 111 II t l il \,i '.,rict IIs, ,ll tiic 1of tlint Hlindi h13' lt+n. <3 l<>s+
,n'li !!-. tl,,r n, .t]..l I,., .r -,',*'*I w itll .slitrit sjpiirs< lint c,.|,liln, ,I to+ oneI

|,n(l. :it2' .1 l.ilet l 1,' ,' i Ll.,l s UHiimll-l"'ll *I c'.r 'nwot3s thait UppIeU i33

l t[l' m '*I I Nl
In1lfiit., -I tlllt: I I lit' J i li t tt, llll, i !l l 1tinct Il,,h i ,,'ll 1l 1
Iyp, v ii li % i\ ,11 1'1, I. 3 )vbr1 li 11cd ti11cntly 11tl i tI I .'_v3 1 t I -1 it 1
]nit+\ l~e' ,-i',, l ri.-l.qt l 111.nI l,'\ i ll {J+ (* +l+i-tU-t ? nie+ i+Ivl rc])>ts+! ln +,s i ltnc

IV liVt, Cr l'i'ii -. I 1 \.il .is(il i hhII tte I. .1 i 11, W whether the two
tivp .- \\rit ,n t..int:|ll\ ,l,.t nir+t or noitt niiiyt iniikt+ litthf *lII;, tivnc( w+itlh
tint lpi ie 1.' ii l, [',.,' sp eei is tol 1< iti (hlitiiilf c'pli'ntl ct oa f t li
iil iirLc, ll,'nli :\3.[ nii,' ,I "lI li indi coi ttolIt' cith)r as 1 tin3 iie ,i...,'i r,,,l-
xxiIld |lii,,nt ,,1 ;,-. ,1 l,,.n -.i ,, uted v+ariety+. It wou+t+ ld d ubtless the ea;+sy



t> lii l I I I, r l. I I I, ii ,n u s I f1ifo pte i tt o k 111 the .sa <*
w i tlii -.l,' I -i,,, 111 1, I I Ilish t 'i1ifor ll C t | i~ fIi+ it iiott' 331 iiit f ito
,,I" tli, i'.i.'vp .' i nT '''.i l'ii 1.ut, it is + ty[pe thi t w oul+t d hur+Idl\ invite
<'ilti\ lt1,iio ,. ii,. 1,112,,,..:11' si, ,i._', A U'-\l th e ltw 1t3to 1
,..nlnlrnt ,i pI,'.il -l,,,i :- Itescribe l iIn l\"'. ]' In '~ir-alo t i r



1 r, ].h e i h, I I I l_ Lt I t I I i en
!:in~l F~ln'hl,' i- ,,.,li,,', t,, helirve thieit this WHS| the' prototype of the1
[in llm ,'ntlii. "1"lI,, l^.'. plit ,i co tton itself is supposed it, have been

thli-roi ,'kh l t] 1, ti:",,'l l-. |' t l dt on y o tn mpc l'nU itreyi- ",n l '1 eve o

'It 'llllit I lllr t,, Jf'i 1 d j Itt It ."
"i'l'| ,, .... lt' na l :,l,., i r, ,, i nt e ttcr n i al tt 1 ( >la n t s I+ a y', h v t atk e n t t, a n
inli,.'iti,,ii Illi:,! ,,,', ri ,',i ,11, ,'1,n -lli_" within ttlnxli ia~s been avoidded


i I,. l. l i iii r, ',l l'q tian stocks, utI it a.t a few i i-

ti uV Si ,II f V! I1 i ,r. 1 f I .,. I i dI type 1av bee l, i all. 1 .
t'eiiiit'k ihl\. 'l.,-~ -i~iiini.nl in,. ..I" thec extremte l i d |,,, !,.:Iil-, ill ,ill of tlie
iu-lv ini+,npo,',l -\,,, ],~ .,i-i* -,ip|,,, t~s tlie ideai thiat such [itl.,ii- teli+
re.,e ilt ,*oii|lrh l,' i, -. -,,, .+ It. is verO y ,ln lli. li tit believe that iill
thIP ,.irk.. lI ,,, lI.nl, ifl"' ~-.m e ,w .|. ;>.. iin lli,,s o.f -,', ,iii,,'_ recent im te'r-
inixt irt'ti. l ,, I" I H ind I|M,,|. -,e l nI,. e 1ii.-i ,,' ,, ,,I the rInrind
l pltnts 'II'rc '.1- iillrni .iln ;,,irti t el~ teius +lv s as+ the F'._'.x pt!.i ipltnt~s itn
Ethc s~lin, ..iii,_', of ;iii liniiitt~ization.+ Indeed, IlL,'\ :,ii[':nJ" even tinore
*' S ,. I-'[,,i, h,.r 1' I ll, I,:ri.,,i of he 1 -', r' i.,'l 1 n '.+ , i ."' *+ S, ,. i n l1. .1. ,.n ,1
'ivi>l 2. n, J N \. ,,l,,r I' 1 ," ,- ,
"2-7297- 1 it. ".. I." '








10 .\i L' \I I I'- Iii-vEISIOY( S IN ('O'"oN.

iiiiifl'riii. perhaps as ;i result of' tlie strong contrast between tnem
and the normal Egyp)tian 1)lints.
If the Hindi plants stood alone, they would be identified at once
as members of a series of Mexican cottons related to our Uplai type,
but with definite difference,. Some if the varieties contain many
plants that combine thlie Egyptian with tie Ilindi characters, plants
that may be viewed as oiulinaiv Ihybrids, but tlie persistence and
remarkable uniformity of tlie HI inldi type can Iardlv be understood
except by the analogy of comI)lete reversions: to thie f'pland type
already known in experiments with gyptian-Upla nil hybrids.
CONTRASTED CHARACTERS OF COTTON REVERSIONS.
Though complete reversion Ima n,,t have been formally recognized
as a phenomenon of hIeredlity, it is believed tliat an examination of
related facts will sho\w a verv- general I tenlencv of reversions to
extreme expression of charlacters rat iher than to slight ,r intermediate
expression. Even whien nIIil ine character apl)pears to be changed
there is more likely to he ;a 'onplete clhanie tlian a partial one.
Unifoi iii. deep-red ears are a much more freqiuetlnt reversion in corn
than ears that are pale red or that have only a part of thlie kernels
red. Black lambs artC generally black all over, and only very rarely
spotted, except upon tlie IheadI. This remains true even when black
iiiales are regularly bred with white females, as on tlie elevated
plateaus of Guateniilai where the Indians prefer thle black wool.
A few-piebald sheep were finally seen in mone Ilock, but only after
many of the miixed fhlock- InaI bieen looked over in vain.
Similarly accentuated contIrast re I I'iund ,I between the Egyptian
cotton and the Iindli. Thie veins of tlie leatf if thlie Iindi cotton are
united at the base int, a larger ainI[ niore pnlnminent cushion, or
pilviiiiis. than in the gyptian cotton, andI tlhe p)ulvinus of the Hlindi
cotton is rendered [lie Jlire conq)icuous by its red color, which is
shared by the upper side of tlie .-,)imiewhat swollen end of the petiole,
for about half an inch. In ,ii l riil. Egyptian cotton thle pulvinus is
pale green, like the atler l)ol'it in o if tite veins, or only slightly tinged
with rvili.,i like the endl ,if tlie, petiole. Under some conditions the
stalks and petioles itf tli Eg.pltinn cotton take on a bright-red color
like the pulvinus of tlie Hindi. but inII spite if tlie reddening of most
of tlie petiole the -wolhlen tcriiin ,l part and lie i)pulvinus of the
l>,^ypti;, leaf remain iistint lY pImler. Exactly those parts that are
tlie most promptly :ild dleepllY Iet'ddlend in thlie llindi plants are per-
sistentl paler in the i'gyplt i.1i.
The stalks ;.1d petiles of tlie Hind i points Ima v also redden with
age, as in the Egy-ptini. a id I\%Iei tIiis occur s tlie contrast of color
is dh-.trovedI. for the ril -if ti-e )ulvinus andi thlie swollen end of the
[tir. 53]







M.IL 1 I I 1:J. I i IN-' l i i 'I .


petioIe fiih., -)III.. '., I Ilil I -' II- rt be aome paler ti than the remainder




or I Ii cant pv it dv.* -it, III If-- lIz "111w I. e'I en 1131 I Ier t o I Ic pe t Io I~
o( ti 11'I l It hI, 11 111 I it'll pi 11en n l 1ed o ition w If th e \' j'-INti'n
It liii 1 n l r \en1 1i i l. II I Ilid i i latsr t h e ver \,.i ,-. lie 1 wI
w itp e I-I, zit I I N i -.l I I lI I' l<1 I1 I III 11! IIIl.ini 4l1
l ilt- t il l lln I I'% I. 'Il Ili ,, I ,I ji< tltc c'ltl r ah le. b lt i t II lltl 'l ,ver1





st~ilt hI- I Izl Ie v II II
inl, tilln I I.ti 3 ', Ij liel,'- If 1 ilr, s tme palt ThI Hindi Ie tton1 like
tIle K nkiii :anel ,,l,, I 'rri \ ,l C intii ii I'. Y" (f tI,' hle \ tlo r\. Iw t 1d
tit llv i \ii I k Vrl l r i, l \ i r Idd I I p rI l *'I < I< p I iti (lh nl ke d oh r
wiale tll:ili f\lit .I 'I.l I rr%%If 1v Ir. l t, i even Il n th l re t o f thn e 1 etiole I
ile..r Ivel i ll \ I ,, I i '.\ li 1:111 hotix < te t ha1-t1r t I ile pI e tiolt



a.t' }iriierwil\' iizikei.I liii [) l' li i ro anii '! oift t ao r l ~ I'ii it"n t eiii alliJ1
pah.iir t t h i lr. .ri ,l m .,,. I. lilr kt iii cthoe naked tmvl rIl. Tir.

esprl .t'iiily Iva ,,,,IIII. l i,,i'i h
Ap hin ili,, ('-- iiii" i|)l,.l.\ i to mv a tlnli,,n lt r 1til i \ I',l ini Nl Gii IIf the Mi, ri.is varieties
of t'vorn i i l Ihv Ih iv ali .,alhI il i lctr hi :ibet, ,,,.'y ]k,.l. \lIil,. otherfe
hv.'e titx in i lnl ci a., 't iiil hlthaIn d \t itr in 4roil t 41f lin< Imi+i. The
gontrm ,,t iA, .(-l ari iii t -.l i i Iril .iled I tn t.i fa ot hl t tri 0 liwatlla tht
arle th 'erwisn ik il 1i t'i r .1%v i rk w t)an el rf nl .,I' ,nLd ethe l a etll .' ,
while ill.- iii,, _-.1i:l Ibliind i' ,.ik l in tOw tb e ri1 tlmht Ih ve tila i airyn
shealhs.
REVERSION IMPLIES CONTINUED TRANSMISSION.
TIhe ftil ,l -i f ,i,-,iiai- t Thi. T,,.rsio r Iave a practical t1 euri,._ upon
problems of hrnv'dlin.. m : ,iil I, ,liin.I I.' TheY \\w1-1 uts not t) r,.I\
upon tlti li,111, ,,f ''ii0 i i'i lit I ;i il I i conl[ht hte eliturinationll of lcnda -
sir tloli' rln -.sl-I'ltl T 'rtr (1e0.s not1 r t. h r ii I .., lire t hntion l IItween (Il ie visible
expr.ssi, m if ('|I1 I,: iI l, ill .i II. lnit ;I l ti eir i nvisilhit trvI sI n issito in the
germ cell.. ('ni r.i ',i I] .1 I rI rn' in I tll t in O ldA C....',.r t r.,il ,' mh a be-v
come lileant ili ,i, ii.I. A. -.i, k tii t ap1pea rs, p.r1, utmer oAe setr of
eon lit i,,i-. ,,,.,y v.,i|'l"'e, ,i .,,in, ,tI,,r ilh e to I~e seriously eontiiniinit(,d.
Th hiieItni I ri- i i-.1 ii.', I..lI .111 und1 sirai le chara ter does fo Iarm
t es ln s lit'e ] l,'i 1. i ', i ,.ntin t rs', but thie return ,.dl" ti t thar-
1t e ir to" .xI ''- i'Ii ii..n' lll i 1' mu injury in A c op likeh tiet _.' ptiati

Cottln. \u lh .rrt, fill, 11,,t',i ,i ,, \ *,[ .4 e lilt' ,r is 1 prini e recquisite.
Experimeiu,.nt- \\il,, ,,t l. n,,t itlifiite thai tenldentcies to reI er-
s i o n'I ;lr e lim it,,, i,, p,.tt i l, it L dt e s c'e ntd a t st + o r t o+ i ii _.t,. clhiir a ct+.t rs+
Sting; i h 'nlrpIi. 1\ . .. t++,.tilnes iiif0rretI lt,,i1 1 the behavior o1f
Meiidtli.'tn lIyvl} Id-. '1ttK']:!, i, _',Il ,,+ M'in. ,t ii.,;, rehlitio}ns arie fo}und in
co tt o n, tl n, pi, I i'i,,, ,i,', ., .,t I,, ,,.,l ty a re e.v idle n tly n o{ t liiiii .+tl t o th e
strictly Mend Ii.iii m Ii. I 'tween the chtiiracters. Students ..I
Mc ttnlis I uiv IIIll r I lI. 'll -tudies' to reaction I betwIeen Ivarieties
[Lir. .5i3







]2 Mi 'TATIVI. {iF 1-{% H II.\S IN (clI'TT(IN.

tli.i hivetb b rq'll riuglit int, ;i a. odiition -d' uniforni expression of
(li.ir'ictlcrs-. hut ithecr kindd, if re;ctidis arie not less,; interesting and
inip, 'rt;liit. The II uniftriily or "br'evedling true" ft' r few generations
(1I ii li\ iuluals doIeb' nhit sd 11:11 ;i s;i o k is pure -'in tIf l ense eIs cm-
pk.I v ib lla V Writci s ,,n M diiiII'lisi, l'lii iu,1,a i li;t tlie Mendelian
r,.uln i Il.-,,' X \pr,,ssi,'n ltt i i e lt iir.Cc ,' III I ltsit" bsill c I t'I of thlie
11 l.i1i,.t(r'S is A di C i'vlliiilt zi. Ui.miptloll whlien tlii' typical Mendelian
i,,l' \ior .iJappe.ars. Int r-'vrvtlSiitnis. f latentn" characters show that
S\|> ii 'ii is no co plet Ij e imlex\ of Ir I;iisiiis olI .
'I'll id al,,; tt I it t l i a ,I'slI %, ol l o "r I ultivaict< plants is to be traced
l,.ik ti ilifrmli "' puirc tlick-, fli,.l t(riisiiiittetl mlv single sets of
(.lir;ict'tt'.-. bili,, i \;i rr.iii iii li i r t iuldv d" tlhe lil, )t primu itive types
alid \\ ilil rlz i\nv,'s of ,ur d(,,ist ieul .iied l-. D)iversitv of expres-
-.i111. iiisttlail ,'f iniformiity, is tlic riiul i'n n;t urn,, ;inl tIhe transmission
(it lli dliveris c'liaractii Kistis I dos- nlit I vascIv when unifornmitv of
(exp.llc.shio, is ,,rcbt d t'lii'riuili c.tlectili. lcvcrSiii, show\\ that the
unltl'.'llY i iwll 'it'iiii of dl iv 'siltv iv i It c Impletelv lost, nor tlhe
pti't oif [lie. ;,cf.ints r;aI f.'irattls 1o reappe)a-r. tiVIil after long periods
(of .llipprrv,,,io,
REVERSIONS INTERFERE WITH MENDELIAN EXPRESSION OF
CHARACTERS.
Ti, lb'livtili (s to 1 r(vl si,,ll I,- lip I,, r'ti'koiit', d is, ;i s riious obstacle
tip Hll, litilizli,,lo ,,f l vbrlid v iricli,. ,l,, -s tl cxternal conditions
a1iil tli pri' , of rl ,l'lp i ,'tiilb' i ;,r1. 'inddtr mt i lit'h more complete
c., ll'oI l tliian witli ; in o 'n-ft'lt iliz/.c 11 ficid rIop.
MviclhI j)'iii lt' l p i .t.it .1 v-1r ti-,N ti I tf l kli cti on'i i in slowing that two
kinlds f ('.db1iiniition,. I IiZi 't ls 01r ilq'prtvsitttl among hybrids,
smilen stiblih illn expr,,-i,'iii nilI tithers' tiit;il,,. Intermediate char-
acterse or rtvrisions Iitlt ;IS' (-I ti divLil It ldl ncit'5 of expression
il,,, cii,(ur \w itli nit icli icng liinit in tlin Iii't iicii tlti Cn of a cross, but
Im.p ;V fterwt i' s tlidiinii m' dlisappear. Evtn whinii the first gener-
atiinl -liows iiifi'orilv interlndintc -ltiriacters, thlie later generations
tcinl tI, retv't' ti, iltirt' thielilCt' CxJ)'t.s.iil of ilie parental characters.
Th tI vpival MIndlt'liail r'iatii .lls ;ip'lear in l v'ssts between strains
tlint dlilfer b\ dlt.tllit ttltndencis io bring certain liuaracters to full
expit t..-ill I r i, II'a ve tIlitll \\ it 1ou0t expre;sison, but it does not appear
titii i' .inalh'gies of slicli thiracilt('rs ar' applicable to all kinds of
ipl;iills orli t i ll a ll ss of li\vlridls.
SPilil writer., on Meindlelisii hiiav supposed that nlieritance is
g,'i'ii,'l lprio)l;liiit dIt't-erliiinliIts. dir "'units.." that are entirely
s'p-iraitt' ;illil indvip'll'iicnt s', that some of thliel can be changed with-
otuil list ri)in) tih. r otliert.' like (chiiiizingi tiii liters of a word or the
wordss of ai seltel('nce. Individual \ordls fromii related languages can
('Cir 331







MI I II\ I 1:1 \I ;-I' \ I ,I ii ,


o fl't,'t ll ) IIlilill ',l lilt .1 l \ l'I I I -, ll 1 \\ 1 l1 I,,, I .li-t l l lA I I I ,,
, t It, nI r l v railil lll ,, 111 1l i l lWl lirl' l .1 1ll1l l-i.1I.1 I, r'- ,i|i| i t
It IIt1 -.Ell IL.' if I EIIr I% I I I i. flI' I Il l l lr l \ I .J I I I I
O lltlgi IaI' 1. I llz I ml Ii; 1. .I IIn 1.l |.Iw tir 'r1rl'[ 1 1l ll nl'
l'i I i Itlll t II It 1 1,ll .' l l Irrr 1 1 11' .i l I I I I I i l l, t I I i Nl ,IrI I I I1.' ,
Ie1111 res io l Io l X %r 1 1 1lf -g I I i l I.Ii r Ii I I .l li\ I I W 1 1i |i I I I I fl I I I
I ml ili' L I l.iIl It'II Ii t i iil Pll ii i. I \ l\ti I> ." .i' l I'Ili It I I I'I .

t an',,. then I t'IIi C l t ,:, Il i L'll l lirt I ll ll\,' ir lit..r i t ln r, ..i,,,i-
S tI II tll 'I t \ 'it lll\ llil l'H I i hr I '. i II \r lT ,[- 11 I.'-I l il 1 it- iv .'II ".r_' li ,, i
Ixn e .~ I .\ b.ry~ ids I It' ll i ,.,I- ,:, 11-11.. 1, 1' V. It,.r,.. 1
o if t l' Egy p t I l EIl iri, I I ' l il Il It r. ll rl 11' l i ll.1 1,i ll. r.1 illd r \IT liI I I t, I -


Itga w it l i ll1) Elf f1 ..Iif ll) hui ,, IE. -m iiit,,- I I .Lr ii] 'r -IT l ll t lu -,
Silll\ 11 ( l u litI 1t m01 tt CIlIll Hi 1 \ II Ii t il 1i v I, ]|\ r I em\ i Ii


L'plit I le l.l'it if i tf rit l'v Iii I., i t . n11'.li 1i ,nlI i\ L I l t it rI -11 I .. I -ir lt li
xpt'onl i tll ieiot if KI3vti 'lr antl, ilit.% iimI i- ,- 1ir'_i-.',iv I1i \\:i lmI T.
d If t l( .\ it l 'l iriit Eli l 111 i 1. I lt Imt 1,r- i ,, t.i1'. 1 1 r I m li I 1. I.)
iltI ,ii tlilrt'. ri Et' t iIiE-isI ljaill l tl i t titI II 1 llitI'ii"I, if :I.-
Nihnrelerias is crutIIm l t i\ ti E il i i '' 1 1l:11U4IiiEN 1' .11,0 It :t!i


m hll Yt mi ph un- hlte l i.i' ll' h ; iliE' iiS 11. f i ',.ITi l il i rE I ntl itf t 'Il-
Slti nml ,lit il'fI I'niIvs el{f i ,r'iii 'rII .s t\ l ti iiLt'' ti '.i t Lli ,,I t \\' -,ililtit I
n1111 it h it le i 'r lv r]izirif tfact ll I Eii 1 1 f ih' NI l li r E! n r VI? :ir1' illlll1itlIl -'
llyI l ilT rll:1lf l -' 11I T ill I'llr l-ll :1 1i- d T lr1 :l 1l 1l







Iltra s res l f ifllit' pIE'imlrhizi i !lri> gr:lul.r I IIC' t i t \itili | E 'rff >ltlt it I l- Ntili-
tieliti (if lIlitl v Ih n itt tiiS' f;l irt ?IVZE I111't 1i1.1 i It'll" iIt 1l 1-E i l-'l f i m1Viin.
tw i le ,ifit 1 ivt r.'rg h m-it Y i is ,i1f li\' ri-V fi ll F I, li .li .,11 Ir, .1 i t.,I lil ,1







whnle liut it V ru'inuh -ina )Ill ;If tllt iiiI \ f iE- l f W. f 'lilt'1 1:ni' 11 1 1, zw i itI'
(listiire iILp icne o f r lrt [o s i(iiil t1 l.iin. i -t t E'1 i ,' ll i |iint iil.l lt .r\
Adm its tinhe Irnil z.lt is '.sioin ,f lttt n *lit l:r:,i'f.rl '.- ;, :tI I 'll l'll of tlit I.r'li l f
iiiln'ritiatc',. \%h,,re is M. l, lii i l r it.t'll P i.1\ V i'V.A, il l.Vt.111- v .1- :;il
ex ceptionial l)1irtiii1n,1 1,', i -iirlL. It I'w vl", .,, II.%l liv .' lili in1:tl
t heo)ries.
Mb endelia in .eiolniii.t iiin.o olf ,. .ir... ili> ni,, | 'iii i 1 1 :
Iren at im p )rt ; ai I mI 'ItI II iifi' T vn.-1 i'' 'in r 'f till' ,r, lrbnl1 .I l..I P rIlk ,\,r -
siorns Lii d (',Iirrvl 1itni o.1 'If rh ir t Sr I ilal ilit,.rf.'rr % Ittl I I.1il,. bii l,-
ntiMtons bet er.n 'hin lra.tim lr I,,ri ,,I Ii'( 'rin ili ,. r I'tl t v I it. i u.\ rsi i I,
trLuns hress tIh.n M..ii- iilli [im, -riir l -i. "l'ln\ iitIrf'. i li h riN '.i-
delian (Ilnin inve ,i i l th, first 47vi lte rliiin :Midl \%illi .01'n1 l4.4 ii 0 ',,iil)i-
naltions anil sct n'tS1 iti) .is ,f rhalrtnIl'lr^ il till' ]li,'4T "Vill''M;tlili- A
Mpndpeliin (,iOiii +iIn 'ilil (If thle nukedi s., ibtuntl.nt hl t if ini ll i ii,.-lit l*i rI, l,. Iml iIk(,-s' ll l l l-
[ire prone tij revirt lt s[;irse Ili so O ltiltl- i\ l i. iiwt lik l\" 11 I1,
maintiiined. Fiiz.'v-s dtelld type.'.are r e'rfrn-'el Il'ic i.Si' 41f tll' 'ZTr-itli
aiibundlnce (if lint.
a In a paper read ill a liitn'thi'.' "Ih '*,, I,.'ty l",,I nllul IfrIlh i h 'l4i,.y .1111, u 'h. -i.% ,,,- .
entitled "Sonlic Theor'i" ilt Hrt liiy .' iI % ih,' f *rv--it'I,+lli ,-f S i I,,i-i. r., il ,.l.l
iion to the. Ph mn rnti ihn i ,,I lbri,[li'. i,,i. .\M ,-Ir.1. i in,',i-h,,.t ill tOl.m I'.,i.i,,, .1
G azeli \',l 2'5'. ri 1 1 1, 1,,'*
tilr "..iI







IUL'IAiVE HEV'EII:,IUNS IN COTTON.


REVERSIONS OF LATER GENERATIONS OF HYBRIDS.

.iaiiy at teIlpItS l iave leeIn madIe to obtain early' aind prolific Egyp-
tin11 ,'i Sea lsl;iiil varieties bY crossing withi t'plndl, and the first
rna.ltiits f ,itlh crvrisso's often appear very promising. The dilli-
c'iilit is t i itl,' I, ta.r generationlls ]lnt oinl revert to the parental
tylp.s. Iltt often go farther kick, to the condition of remote uninm-
proved anie-,l.tors. Instead(l f hi miy longer lint han the Egyptian
p)arenli, ias thle Ilirst gei.nlration ustiall v does, the later generations
l>oaiimec iiilferilir ev\ tlle f,,urtli ;niil liftliit'i:ti100, gri ;wl at San Antonio, Tex.., ini the
sve,.asn of 10,)( i l, lii not slihw ;i siLrlde )plant w itli g,,o,41 Egyptian lint,
.1id \very few that wer I better tliian 'rlinIary I'[plfnd. This extreme
dhteriratiol miuglit liet ascribed partly t-o dulverse conditionss. but first-
geileration lihvbril i tr'wnl iundler thle ,;aime conditions 1 rod)Itwed excel-
lent lint, lonIer amid .trong-cr thliill tlie Epyptian parent. These con-
tr.ists l)et\vvci tilte dift'rent gcneraltionrs shiow that tle livbrids do
not lerel" fitil to fix prticul;ir 'conllbiiItlons (if the parental charac-
tetrs, but liiay first exceed tl l parents and t lienl sii'ier serious (leteriora-
tion. The cliiaricte,'s if the lint tliat have received tlie most selec-
ti' uI i tlio\\ ie I tist striking dleterioration. Such hybrids promise to
ihaive practical value only in tile first generatitiolns. The problem of
uttilizatior tilrnus iipoin Ilie possibility of raising commercial quantities
4if lLbridl seed l "
Tire fact that ivlbridtIs of Iater generations (often -,Iow characters
dill'urit froli thlo.e of t lie first generation ias been taken as proof
of tle Melndelianii their of separate, tran.isiission of contrasted char-
avter's. (' haractrs that appear in all of tile individuals of the first
geiiration but iet in all of tliW s.iend i r later geoi'rations have been
u'srilbed to tlie prt'se'nce of two id Ie Ipent lent Mendelian "factors"
that are s.iIppo.el'd to bIe transmitted separately, a nd not recombined
in all tlhe meniieirs of tite later generations, but in only half of them.
Tlis theory would explain why half of thlie second generation might
fail t1o sli-ow a character tlihat aplpeared in all of thlie first generation,
Wut it gives us no suggestion of tlie complete disappearance of the
],)Ig lint in tlire later generations of tihe cotton lihybrids. There is no
reason to suppose thiat thlie internal "'factors" that produce thle long
lint in tli lirst generation of a hybrid cease to be transmitted to tlhe
later generations, but there are serious differences in the external
expression of the characters. Factors that influence thie expression
of characters h1ave to be considered, not merely the possibilities of
alternative t ram.mission. A t'iarracter that Ias been expressed in
,, [ 'i r'-,r-,,,I ziia l Int siiel'i.d C'harcTers in Corlon Hvbrids. Bulletin 147, Bureau
of t'lan IlnduuItr\, S Dl)ept. .\'zricultiuri, 190O p. 1.5.
[Cir 53]









.t'li. liiil '4 i, 11il In' ii.a in-i il i, at I. i nt n imiy I reduc d n o supprtes-d
in litter r"tlliTl't 101t1t.
It nii 1.( t l II,', ,,1 ,:.l ,, i 11 l,' [.t. M 'l fferati e atiot n as i,'ml have leen
sec'uIrveIdI it" thf I 'IpI i i'\ inr1- i l1-T I I 1, 1I C coIs lin t, Ie ii' I ,l '. aI I; I lI I I in ,tlli, iI It%_' tifI- l>t l thi; IvioidrIl
I il Nt -il lelill1.l l' ii ii LiI l V t, I l)ca s t hiel ia (ne1o 11i1 1 to I frltoI I 1
hti' r tnilh liiiii 'Iondit ii of 1 i 'lf-I fr ,ili ( tiF Ii in 1 11 \%f ult ii'es tf \t ll1t1i
ir o i. l,,-..llh I liiiiiirl iIll t:he xi|f i o. duf t vtnli neite i l(siall Itl 1Iiiir
t, tfert I of kill v I ,c h. Ii ll I 11-1 % I I% I I I, I'_ thv x;+. pN ,i :+ i~ i 1 4+ 1 lir rh+ i i ; il h l i ail a
lt'is, liild 1i'vil nt' i l'- 1 1'ln ..', ,r tln Icsn lia!e to- !m\o rialtio'iw
a id i'i'' -. '1'1,l'-, <|lii '-Iicioiw al l' w o rths ,I cari fil ili' Vp tj'L.il ,,l,.
thiili 1 .i h |ili\x-.il, ,,'L' iiil I'll s., t ( 4f line i ~f','' ti, it ll. l n X>I'(HSOi
tire l lil (li iken iinto il ., iill in1 tliv W AI T=.,l'l ,,, is'tl i ", ille '_, l
cells.
I'iiifrii i v I, iiii'1 ~i cIi Ier atio ln l fIIiiv i u aintained :.Ii in,,,-
the i--f'iiliilti. ,,f iiii iii, li i1iii.i.l ul otati an l t illn in i ll i I' stock.
F'rti li t li, diiii, -Iiii 1,,in oint this Ll ,ii tindlielly t lniflrmility
m N Ibe r., k ,t ,d ?I, ili, ,-1lif dill'i' l,, t wt ei tlei [ that
4ti)CI r Its lillit I I i ii i ni Iii l-P that are found .aii ii'i' ha ybridi. "1tl
range o4 v'aiaiiiil liili,,iLl Ilie iutlitioln s aippiai- to he as t 'i il as
ainolii, tn' I, i ,l-. I idi, a d i; raants t tile c\l .i;ili,,i thaLi t ilm(ost ii,\
dlesirailt, .oiniluini ,Iii i I lia racteirs maty he fIound bI pers itentlt
sfarli''.
Tlihe Il)Ieitiint li-l.dliir 'If initiative eve'rsioin to colle tinie from
s.eti .Isuig et.-'t- ii illit it ,--ililit\ of I i.tiili.. (on niiitions of cIiIarac-
teis lbet \ 1e.t, ti I IV% o I I it>- I lWose I hy 6ritk fail to show i W iii i A p ii i,-
Bian re ti ,lif lin-ti ld Ill' iIllliivfn li ,.." to et at lish i lldi;i l, Ulions
between t lie i liii .ie .f -iuch species asli the I-,Lyptlian and Upilail
c )tIt n iiielit ,i in iiai I!> ,' ll' i to tile ocCasio alll unit ivt e revterslions
that pllipai ill diliit, li\lil to -cks. Siluli mutations mi.hi t hotliave
the speci !l iiio nil, fI'yiii of first-generation hibriI- built theiy\
niilht vi1i1 1ii1,4' 111111.i1f, ni plH '..i'i'iy. .A stock of EL"'? it i.ii c(ot tIm I hat
had ionce beein i liyi tl,.i l \ it h Upland ini._'li furinish a serie ,f Qiinuta-
tive v'ilriaio ll 1siilii, |l'il ,illl-'i for l l'- iii,' b)11pu pose thin a stock ,f
diverse hvybril.. 11i, apilliation of this method involves the dliflfi-
cultv oif pi 'lducing i d il givN cii, .i,,l'111 to ii t heo lhe li,_'r, number of
rlevers'ins lhait il iiiiglt niteI lo be inspected before al particular coin-
lbintitio of chliiiraciI,r. ,-.tlhil be found. M.[,,,I f the reversionsll \ ill be
inerhiri, bIi in ,,( ii i= i di superior tyipe may be expected. Even
aniuu thle Ilindli-ik, \n:tiiitions 4l the E.-yplilan .cottotl there are
some that are aliv, e tli iamiL'e of th1e l' '-1p. iiti. in spite of lihe
extreme infe-iirity -if the hlilt characters .-f the extreme Ilindi type.
[Cir.53]




. '.HIxil :]|Yr


%


16 A UI .'I ATIE % I' .[I::SI.'NS IN ('CiTTON.

AGRICULTURAL SIGNIFICANCE OF REVERSIONS.
If tlhe Ibi111i characteristicss contiiLnue to reassert themselves in the
Egyptiann cotton, complete reversion is a less serious obstacle to com-
mercial uniformnit than partial reversion. It is much easier to recog-
nize and dlestrov the complete Hindi plants than the intermediate
individuals tlinat give only slight expressions i' tlie Hindli character-
istics.
in plaitiing.s (f tlhe suu)erior Jannitvitcli aind Nubari varieties the
proportion (if the complete IHindli reversions lias exceeded that of the
plants tliat show an intermediate or partial expression of the Hindi
characters. Thisis in notable contrast with tlie behaviorof a planting
of the older andI less improved Ashluniu variety, where a large pro-
portion of the plants show some of tlie Iindli characters. Whether
these differences should be ascribed tlte more careful breeding of
the Jannovitch andi Nubari varieties or to the different conditions of
the fields is not certain. It may be that tlhe intermediate plants
represent new or relatively recent crosses between the Hindi and
Egyptian furm if plants, rather than partial reversions, but the
large numnibeis if plants thalit show Hindli seedl characters indicate a
very general presence of Hindi tendencies, at least in the Ashmuni
stock. In any case, tlhe recognition of thle complete reversions will
assist the careful planter in learning to detect the Hindi characteris-
tics, even in their less conspicuous degrees of expression.
Hybrids and extreme forms of reversions are not the only types of
deterioration that must be guarded against if the need of a high degree
Sof uniformnity is to be met. Many plants that do not depart from the
Egyptian characteristics will be found to fall far below the standards
of an improved variety, either in fertility or in the qualities of the
lint. There 1-, no reason to suppose that uniformity can be main-
tained without continued selection in any field crop grown from seed."
If reversions were to be looked upon as ordinary hybrids like those
that result from recent crossing, it would appear impracticable to
guard the crop from contamination, and hence impossible to obtain a
uniform commercial product. No matter how carefully the fields of
the Egyptian cotton may be isolated, variations may still occur that
can easily be mistaken for hybrids. The difficulty of securing ade-
quate isolation of the Egyptian cotton will be serious enough in any
regions where Upland cotton is grown, but it need not be exaggerated
by the condensation of stocks that may continue to show reversions
without recent contamination.
The occurrence of reversions in one locality or in one season need
not stand in the wvay of early return to practical uniformity if an
aLocal Adjustment of Cotton Varieties. Bulletin 159 Bureau of Plant Industry,
U. S. Dept. o(,f Agriculture, 1909, pp. 56-62.
[Cir. 51]








idet'quate select tim N i iiiil iiin.l 1inl fu f iilil,' rII1,nditions are pIl
vithCd F1-" nilin,'il" 1 1 ith 1 he \If ,tnli I -hi n'Iii,'tr l' I ,I" tIke plainl. %%ill
t'nble till' lTnd,,ir leh, i c ii.i.,, in 1,. r1,,,ii 'rI .t before thI e time of
lowering, %I) tha I c i 'I--.in Ing; N } I In I It jilaii i,, Ii le avoided. Tend-
('ncies, In % ii lit I II l a l 1 i'.uu Ii in IL I, lin ii ti l le eeds( l III Ia e
rejected \l" 'n I [li, Ilt' e m.ilx eler.i ,ii ;i. i iinl, i in I lie full to -ii ,
lf lih-nil, ... ,, f,, (lIr iI, n'\t N.1.r ,.,,i ipill liI I Thi, influence of tIIll
extenei l nidii ..ll iu n,, rjl 1r1.i',i,-. a- il\ Piii, ,if 1 1anyY inldicatioIns
that lie iinirfriib it \ if tli, 4r, Tj. ai- %%I'l ;i- fli, \ 1i ld If 1lil, \% ill dIt -
pelnd up, 1i.i'nl 1 ina-l 11,'t hw,,,l '%. <.ll i,- l"' l fill'-,ed that is planted.
CONCLUSIONS
T ic phi niimo nitf 1111 n1.1 If Iiif, I,, tl l III I) i Ii, niined to Ihe L'Ala'I-' "
of sinlgh hliairairi ., le'r l ] tu v I -ii l 111 ill nil,. dalla lures from pa irenltal
types and bring. lilrereni -..i,'.-,if % lriIIi :, iri ii, liWrs into expression.
The rtinII n f u," tiidl .t' ri 1 ?i t' I i t, v\ ,\prv-.-iii does not il, peix',
upoi 'e e'n l rlen itli iiitilln. Illt IIIni ,\ ,,I|,H\M| in abrupt, imitative
var'iatiiins af 'k pOlr-lir< "-tl,,k-', ihini li bv,, VI.,. -elected f,'r tile Inni-
furim' expre'..iii, (if ,i 1 l,,' ''Ifa lif rl tci-.
Reversi,,nI II ,\ l,, nI' IJI.it \>\ \\,I\4 1n fnIItI\,,rable conditions of
envirl'onileiilt and ]lil \a11A x ill 4,X IIIt. ntl fr el',,i ,-.\ with hali ,c-- ,f
t.xterraud l diliun1 'lThe iinifnriirniil\ iif a. Ik in oi e pla e Ii IIl, n'.I
no assurana e i ,I I I liverI,'i\ % ill ii1 i.1 i llI1>'ii, in ano there locality.
I)iverse -liltru (e.i.-(li,'s I ,' 1 11111f, I I. ill i -i I tI I d and I I Iayv retuII'll
to exp e,.-..i in uaftli1z I n rl gtin'inli, tIn-.
Tilhe l'varitl mons nf t lie iierr(iI lyipvs ,,' iatti have ciierni simni-
lauritiev., nin1l 1 it v I)e w rit ii2 'il in pilihi. l '-.'i,..-. The i lWIrW'Ill ritIIf,.
If thle ItIlce.- r'i'] ,liversitii-. I f 'oioii i 1 o ill ie learned from the
-;tu1 ly if m\ i l, r I I ii p, I ,Ii> d I i ypI.- .iIlI froi' i i li, diversities I hlit in-
ierferie wit die Mivnihel'lian ,xp\I)ie--L,,Ifi ,f ,'li ia<1 1els i In \ Iiriill.
The iillifol'nlhity ,f t 'll" piI| -,i'l f IlliIt it i\, \, iatiolns renders, them
greatly I UI pe'ri,"r In 11l'riI- fr lI t',liiL' 111l)i-'-' Tie p ssibility
of obtainingi, -uiivri'mii lliilii, icvrer-ini- firnii later generations of
dilute hybrid ...lck- i-. 1 ,Wrtilv -f iilvl'i\-tl iil. ,'-I',i;dl\ in 0a es
where dtesiriaillli t 'Ind I liiIi Ci-,- ii lil it i"II airll nit ,btain ed in the earlier
,.enerations ,f Ivnrii. I
The Hindi \vriii ili,- 'if ii, l.. lt piiii -ililir in their charaictei
and behavi,, ti, ,.nI,,e 'If lli, r'\ver'-iiin, thit a appearr in I planil varie-
ties and 1m1i prI, 'v t I h 1'f, rin,- if rive'. r-i t ralh Ier than results of
recent eon nlilinal lit l wii i li -il,'t t yp I If ri'titon.
The in re p i' i)ntll, llul filn- ..f rt' 'r'-iiii ill t'plunhd ci,, iIl. like' the
ilIndi an'itlions ,f til, l.,Iy)tialn ,'lliilil. :il't ie'a lilv di-tlizii il.d.h Ii,
vegetative ('hil ra'L t 'l-. 1 1 lii1at a I Ivv ';i it r' '.1",l. i oUt before ti, time
Ctr. 5.]


.\l l .\LI\1 1;0l\l,.% .\ I tN (I [ LL -% .






MUTATIVE REVERSIONS IN COTTON.


of lowering, to avoid the contamination of thle stock by cross-
pollination.
Partial expressions of Hlindi anti other inferior characters can often
be detected in tlie lint andi seed, even when not shown in the vegeta-
tive characters of the plants. Such tendencies are to be taken into
account in the annual selection of beed.
It is also of practical importance to distinguish between the HIindi
variations of the Egyptian cotton andi the variations that result from
ciTOssing with Upland cotton. If reversions are mistaken for results
of recent hybridization it may appear impossible to guard the Egyp-
tian or other superior types of cotton from Upland contamination,
thougli there is every reason to believe that distances of a few miles
will afford complete isolation.

Approved:
JAMES WII.SON,
St.rtltar'I of Algrticulturt.

WVASHIINGTON, D. C., "ebrutary 2. 1910.
[Cir. 63

0





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UNIVERSITY OF FLORIDA
3 1262 08928 9903


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