Experiments on the effect of muscular work upon the digestiblity of food and the metabolism of nitrogen. Conducted at th...

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Title:
Experiments on the effect of muscular work upon the digestiblity of food and the metabolism of nitrogen. Conducted at the University of Tennessee, 1899-1900
Series Title:
U.S. Dept. of agriculture. Office of experiment stations. Bulletin
Physical Description:
43 p. : incl. tables. ; 23 cm.
Language:
English
Creator:
Wait, Charles Edmund, 1849-1923
Publisher:
Govt. Print. Office
Place of Publication:
Washington
Publication Date:

Subjects

Subjects / Keywords:
Metabolism   ( lcsh )
Digestion   ( lcsh )
Nitrogen   ( lcsh )
Genre:
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
By Chas. E. Wait ...

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 029605743
oclc - 28974108
lccn - agr09002657
Classification:
lcc - TX551 .W13 1902
System ID:
AA00014583:00001


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NTS ON THE EFFECT OF MUSCULAR WORK

|;THE DIGESTIBILITY OF FOOD AND


TIE METABOLISM OF NITROGEN.


CONDUCTED AT THE

j4IXNIVERSITY OF TENNESSEE,

18S99-1900.









" H AS. E. WAIT, Ph.. D.. F


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OFFICE OF EXPERIMENT STATIONS.

A. C. TRUE, Ph. D., Director. .. ::iI
E. W. ALLEN, Ph. D., Assistant Director and Editor of Experiment actionn Record.
C. F. LANGWORTHY, Ph. D., Editor and Expert on Foods and Animal Productio.n. ..

NUTRITION INVESTIGATIONS, MIDDLETOWN, CONN.

W. 0. ATWATER, Ph. D., Chief of Nutrition Investigations.
C. D. WOODS, B. S., Special Agent at Orono, Me.
F. G. BENEDICT, Ph. D., Physiological Chemist.
R. D. MILNER, Ph. B., Editorial Assistant. ...'...




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LETTER OF TRANSMITTAL.


U. S. DEPARTMENT OF AGRICULTURE,
OFFICE OF EXPERIMENT STATIONS,
:Washington, D. C., July 5, 1902.
e: eI: I have the honor to transmit herewith a report on experiments
on the effect of muscular work upon the digestibility of food and the
ebolism of nitrogen conducted at the University of Tennessee in
899 and 1900 by Charles E. Wait, professor of chemistry, under the
?immediate supervision of Prof. W. 0. Atwater, chief of nutrition inves-
Sti:gations. These studies form a part of the nutrition investigations,
'conducted under the auspices of this Office, to gather information
regarding the food habits in different regions, the comparative values
f different foods, the laws of nutrition, and related topics. In making
ihese investigations Professor Wait was assisted by Messrs. C. O. Hill,
W. K. Hunter, C. A. Mooers, and C. G. Schenk, of the department of
e hemistry of the University of Tennessee. The present investigations
supplement earlier work at the same institution on the effect of muscu-
l~r work on digestion and metabolism, questions which are of great
importance, and concerning which there is little information available.
|:iIt is believed that the present investigation is a valuable contribution
to the subject.
The report is therefore submitted with the recommendation that it
: e published as Bulletin No. 117 of this Office.
Respectfully, A. C. TRUE,
Director.
Hon. JAMES WILSON,
Secretary of Agriculture.







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CONTENTS.
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.lI'IpAtiO n, sampling, and analysis of food materials....................... 8
opposition of food materials and feces.................................... 9
tEile of the experiments carried on in 1899-1900.......................... 11
I.. experiment No. 17 ................................................ 11








SExperiment No. 18-..-...... .. .......-..-........................ 14
experiment t No. 19.................................... ............... 17
....' Experiment No. 20......................................................... 20
Ex::''':."::ijxperiment No. 21................................................... 23
:;:";;. "Experiment No. 22.......... .. ..................................... 26
Ea.-- experiment No. 23..................................-.............. 29
......iment No 24................................................... 32







Experiment No. 25............-..- .......---...--- ..- ..---....----.--.. 35
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I iiiof ff digestibility .... .------------- ------ ----- ---- 38
i Wls ofth nitrogient cariedo..- in189- 190.0-.---------.------.-- ..--- 39I






B p eri mesn 17 -.-. .-. -.---- -.-..-..-...-...--......-...------- 40
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-n Nbtducion--- ---------- ----------------------------------------- 7

()mpoutio offoo maerils nd ece----------------------------------9
Experiment No. 17----------------------------- --------------------1
,*A ...... ..Experiment No. 18------------------------------------------------142

Experiment No. 20 -----------------------------------------------205
..iia Exeimn No.fiiet 22-----------t-------------- ----------------26
Experment nio2en 5...------------------------------------3 .


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MUSCULAR WORK AND ITS EFFECT UPON DIGES-
TION AND METABOLISM


INTRODUCTION.

With a view to learning something of the food requirements when
muscular work is performed and of the digestibility of the diet and
the income and outgo of nitrogen under conditions of varying muscu-
S lar work; experiments have been carried on for several years at the
.: University of Tennessee. The effect of muscular work upon the
Metabolism of nitrogen has been often studied in the past, as has also
the question of diet when different amounts of muscular work are
performed. Many of the previous nutrition investigations conducted
under the auspices of this Department have had to do with these
problems' It appears that comparatively few experiments with man
have been made to'determine the influence of muscular work upon the
digestion of food.
The results of the earlier experiments on this subject at the Univer-
i::,sity of Tennessee have been reported in previous publications of this
;Offi.ce." The present bulletin reports the results of nine additional
experiments (Nos. 17-25, inclusive) conducted in 1900, which were
::; divided into three sets of three experiments each. With one excep-
Stion, each of the experiments covered twelve consecutive days, being
H| divided into three periods of four days each. In every case muscular
work was performed during the second period, while in the first and
Third periods as little muscular work was performed as possible.
"In the first series of experiments (Nos. 17-19) the diet furnished a
=:f normal amount of protein and energy, and was the same in all three
Periods. In the second series (experiments Nos. 20-22) the diet in the
first and third, or rest periods, furnished several grams less nitrogen
and 500-600 calories less energy than a normal diet. During the sec-
ond or work period the nitrogen content of the ration was unchanged,
while the energy value was increased some 500 or 600 calories. In other
words, the energy was brought up to the normal. In the third series
of experiments (Nos. 23-25) the diet was uniform throughout the
experiment, and in both rest and work periods furnished less protein
"and less energy than a normal diet.

s U. S. Dept Agr., Office of Experiment Stations Buls. 75,89, 98, and 109.
SU. S. Dept. Agr., Office of Experiment Stations Buls. 53 and 89.

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The subjects of the experiments were the same three healthy':
men with whom the earlier tests had been made.
The food consisted of such articles as gelatin, milk, oatmeal,
chips, rice, coffee, butter, eggs, and sugar, combined in such a
to form a simple mixed diet of reasonable palatability. The diet
somewhat simpler than in the experiments previously reported ....
The digestibility of the ration was determined by the usual n i
ods, which have been described in earlier publications of this O3n:i
The food and feces were analyzed, the latter being separated by n f
of charcoal taken in gelatin capsules.
The income and outgo of nitrogen was also studied. In addition.! *.
determining the total amount of urine and its nitrogen content doi .se .
minations were made of the amount and proportions of nitrogen i ...i
urine corresponding to eight-hour periods during the second or foi
periods, as it was believed that any effects of muscular work .ons ii
excretion of nitrogen might be thus more readily observed. Simili
determinations were made during the third period to learn w ihetherii
the muscular work produced effects which were noticeable after t i
work had ceased. In most of the experiments these determination I
were also made for purposes of comparison in the first rest periodd.,ii:::
The external muscular work consisted in walking up and down rai
hill 140 feet high on a smooth path. The amount of muscular w. .~ii::
which can be measured in such cases is the product of the body weig'i.
of the subject, the number of feet which his body is vertically nai .. .
each trip, and the number of trips, that is, weight multiplied by xuil; ,m-:.
ber of trips uphill multiplied by 140 feet equals foot-pounds of wor :'..
So far as is known, the energy expended for the motion of .forwa!rdii.'.'
progression has never been satisfactorily measured with man.
amount of work performed by a man walking downhill is also unkn.o"
It is certain, therefore, that more work was performed by the suba
than is shown by the method of calculation followed. While it his`:Z
be regretted that the total amount of work could not be acc~uiiri
measured, the results are sufficient for the purposes of the experimonl4 -
since the object was to require of the subject an amount of mas.ularZi.
work sufficient to produce fatigue and to compare the results with !
different subjects under the experimental conditions. So far as .ai.:'
extended review of the literature shows, the factors which were ..not i
measured in these experiments have not been taken into account in slii-:i"
lar experiments reported by other investigators.
PREPARATION, SAMPLING, AND ANALYSIS OF FOOD MATERIAL.
As stated above, the diet followed in these experiments was
and made up of a comparatively small number of articles. The fO.
Dept. Agr., Office of Experiment Stations Bul. 53 nd 8
b U. S. Dept. Agr., Office of Experiment Stations Buls. 53 and 85.
SU. S. Dept. Agr., Ofice of Experiment Stations Bul. 21 and 8. ......
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were of such a nature that it is believed little difficulty would
experience in obtaining a comparatively large supply of practi-
A: uniform composition, a matter of considerable importance in
timents in which it is desired to have a diet furnishing uniform
eunts of nutrients and energy. The milk, butter, coffee, sugar,
,and eggs were the usual products. The bread was made from
4.t t wheat flour and was the so-called Vienna loaf. The gelatin was
Sof the ordinary commercial products, as was also the rolled oats
ped. The potato chips were prepared by frying very thin slices of
potato in deep fat until light brown. Care was taken to secure repre-
sentative samples of all food materials for analysis. The milk was
purchased fresh each day, an aliquot portion taken as a sample, and
these portions united to form a composite sample for the whole period.
Te oatmeal was sampled before cooking. In the case of bread, rep-
tisentative slices from each loaf served as samples.

COMPOSITION OF FOOD MATERIALS AND FECES.

i"ThY composition of the foods and feces was determined by the
analytical methods adopted by the Association of Official Agricultural
Qemnists,, with such modifications as have been suggested by Atwater
nd "Woods,b and with minor variations which experience in this labora-
Shas shown to be desirable.
The heats of combustion of the samples of food materials and excre-
products were not determined in these experiments. The values
energyy given in the tables of the different experiments were cal-
$td. The energy of the food materials was calculated from the
*ina -nutrients of the diet bj the factors 5.65 calories per gram of
4iotein, 9.40 calories per gram of fat, and 4.15 calories per gram of
carbohydrates.c The energy of the feces for the rest and work experi-
jients was calculated from the total organic matters of the feces by
:of the average heat of combustion per gram of feces in the rest
Work experiments of 1897-1899, viz," 5.19 calories per gram in
rest experiments and 5.42 calories per gram in the work experiments.
.| energy of the urine was computed by assuming that for every
of protein in the digested material there would be 1.25 calories
e lost in the organic matter of the urine.e
bll shows the composition of the food materials and Table 2 the
tion of the water-free feces. The proportion of nitrogen in
materials and feces is included in the tables, as well as the

SAgr., Division of Chemistry Bul. 46, revised.
ot (Storm) Station Report, 1891, p. 47, and U. S. Dept. Agr., Office of
k t"ios But 21.
: (:Stor:) Station Report, 1899, p. 104.
Agn.,Office of Experiment Stations Bul. 89, p. 15.
Agr Ofice of Experiment Stations Bul. 53, p. 28.











protein which represents the total nitrogen multiplied by l
6.25. It is recognized that the use of this factor involves more
error, especially in the case of cereals; but as it has been morei
ally used than any other factor in computing the results of
experiments it has been retained. Should it seem desirable .
time to recalculate the results, making use of other factors, thi sg'
be readily done from the statistics published in this report....

TABLE 1.-Composition offood materials. .

Labora-
aorsProtein Fat Carbohy-
tOry Food materials. Water. Nitrogen. roN 6 Fat.
num-b (1x .25).
ber.

Per cent. Per cent. Per cent. Per cent. Per ewt. 'l i
449 Eggs............................. 73.67 2.08 13.00 11.17 ..........
486 Butter.......................... .. 11.69 .22 1.39 83.86 ..........
508 .....do ......................... 8.27 .24 1.56 87.48 ........
528 .....do......................... 11.05 .30 1.89 84.79 ....... .
481 Milk............................ 85.88 .59 3.69 4.61 5.1 .. -.
494 ....do ......................... 86.26 .55 3.44 4.54 0 ..
499 ....-do....--......-- ........-... 86.30 .57 3.56 4.46 t 4.86
504 .....do.......................... 86.18 .58 3.63 4.72 4.67 :::
515 .....do.......................... 86.23 .56 3.50 4.94 4.86
520 .....do .......................... 85.96 .56 3.50 4.94 4.85
525 .....do ............. ........... 86.51 .55 3.44 4.65 4.6 .
535 .....do.......................... 86.42 .54 3.38 4.65 4,L2
540 .....do .......................... 85.98 .54 3.38 5.02 4.88 .
480 Gelatin......................... 1.00 .75 4.69 .36 9.82 .
482 Oatmeal........................ 6.94 2.27 14.19 7.01 69.99 ; :f
505 .....do .......................... 8.25 2.45 15.31 7.18 67.20 ,
485 Rice ........................... 8.62 1.33 8.31 .41 82.14
484 Wheat bread ................... 32.49 1.52 .9.51 1.17 F :
507 .-..do ........................... 31.81 1.51 9.42 1.25 56.05 -.
527 .....do .......................... 31.81 1.59 9.94 1.27 6 5.92 .i
483 Potato chips.................... 4.88 .78 4.88 30.78 -56.37 8A
506 ...do ......................... 3.73 1.20 7.50 36.68 47.80
526 .....do .......................... 3.01 1.25 7.81 33.34 51.05 "
Sugar-............100.0A .,,, s-, .
Sugar.................... ........ .. .......... .......... .......... .......... .
Coffee ................................ ... .......... .......... .......... ...... -. -
Coffee---------------------------------------------------|


TABLE 2.-Composition of water-free substance offeces.
-----------------------------------------------------""-... .** ..... f::^Se i
Labora- :
1G!V Protein Carbo -
tory Sample. Nitrogen. (Nx6.25 Fat. Y:
nuber.- 6.25). drte. .:
ber. ..


Per cent. Per cent. Per cent. Per cent. r
490 Feces .................................... 4.77 29.83 15.72 29.05
491 .....do..................................... 4.98 31.13 25.53 23.78
492 .....do..................................... 4.69 29.32 24.24 26. "73
495 .....do..................................... 4.98 31.13 14.60 29.11
496 .....do ..................................... 4.96 31.02 25.69' 23.41
497 .....do......... ........ .................. 4.44 27.77 30.50 21.65
500 .....do..................................... 4.92 30.78 13.51 29.16
501 .....do ..................................... 5.10 31.89 23.98 23.06
502 .....do..................................... 4.83 30.22 23.97 25.40
511 .....do............................... ..... 4.76 29.76 22.91 19.29
512 .....do..................................... 5.00 31.24 30.38 15.30
513 .....do .................................... 4.71 29.40 31.99 16.93
516 .....do...........- ......................... 4.88 30.48 22.53 21.98
517 .....do..................................... 4.87 30.44 33.23 14.18
518 .....do..................................... 4.59 28.67 36.13 15.67
521..... do.............. .................... .. 5.00 31.27 19.66 22.43
522 .....do....... ............................ 4.93 30.80 29.23 16.58
523 .....do.....--.....- -......-- ..--...--...- -.. 4.82 30.14 25.49 22.03
531.....do...................-- .................. 4.91 80.71 18.38 23.81
532 .....do....-.....--- .............-- --- ...... 5.09 31.80 18.64 26. .6
533 .....do............................ ..... 4.85 30.33 16.57 .28.91
536 do.....do...........................- ........ 4.93 30.84 20.07 22.66 '.
537 .....do .................................... 5.12 32.01 27.55 18.9
538 .....do............................---...... 5.02 31.35 28.18 18.03
541 .....do..................................... 4.86 30.39 21.77 20.59 -
542 .....do .................................... 5.20 32.49 27.13 19.43
543 .....do..................................... 4.87 30.41 34.08 14.55
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DETAILS OF THE EXPERIMENTS- CARRIED ON IN 1899-1900.

: The experiments recorded in the present report were conducted in the
Inter of 1899-1900, and were so arranged that each experiment was
..errid on with the three different subjects simultaneously. The sup-
er preceding each experiment consisted largely of bread and milk,
And the experimental period in every case commenced with breakfast.
.With this meal the lampblack used to color the feces and to permit a
separation of portions pertaining to the diet under investigation was
taken. In the earlier investigations the experiment proper was pre-
Sceded by a period in which the diet was adjusted so that the subject
I was in nitrogen equilibrium. This plan was not followed in the pres-
i'ent investigation, as (judging by the experience then gained) it was not
Necessary.

S; EXPERIMENT NO. 17.

This experiment was carried on with a chemist 30 years of age, in
S..good health. The experiment was divided into three periods of four
Says each. During the second period the subject made 74 trips up
: and down hill. This was calculated as equivalent to 1,617,122 foot-
: pounds or 55,876 kilogrammeters of work. The mechanical equivalent
:of one calorie is, in round numbers, 3,100 foot-pounds. The heat
: equivalent for the work measured for the four days was, therefore,
i: 130 calories, or 32 calories per day. As previously stated, the actual
Work performed must have been considerably more than the amount
I' thus estimated.
I bject.--Chemist, 30 years of age.
SWeight (without clothing).-At the beginning of the experiment 68.6 kilograms (151
pounds); at the end of the first period 68.2 kilograms (150 pounds). During the
Remainder of the experiment the weight remained unchanged.
Duration.-The experiment began with breakfast, December 9; the second period
': with breakfast, December 13, and the third period with breakfast, December 17.
SEach period, therefore, occupied four days.
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TABLE 3.--Remuls of eperiente No. 17.


Food materials.


FIBST PERIOD
(REST).
Digestion experiment
No. 206.

Eggs..............
Butter............
Milk............
Gelatin............
Oatmeal..........
Rice..............
Bread ............
Potato chips.......
Sugar.............
Coffee ............


Total.......


Feces (water-free).
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ............

SECOND PERIOD
(WORK).
Digestion experiment
No. 207.
Eggs...............
Butter ............
M ilk...............
Gelatin ..........
Oatmeal...........
Rice..............
Bread ............
Potato chips.......
Sugar................
Coffee .............


Total .......


Feees (water-free).
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ............

THIRD PERIOD
(REST).
Digestion experiment
No. 208.
Eggs..............
Butter ............
M ilk...............
Gelatin ............
Oatmeal..........
Rice..............
Bread .............
Potato chips.......
Sugar.............
Coffee .............


Total ........


Feces (water-free).
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ............


Weight
of ma-
terial.


______ -_ -I-----


Total
organic
matter.


Nitro-
gen.


Protein.


Fat.


Carbohy-
dratea.


AtOh .


I III4


Grams.
364
120
8,000
100
320
120
1,200
40
320
800


147
7,020


364
120
8,000
100
320
120
1,200
40
320
800


Grams.
88
108
1,072
99
291
109
800
37
320
2


Grams.
7.57
.26
47.20
.75
7.26
1.60
18.24
.31
.32


Grams.
47
2
295
5
45
10
114
2

2


Grams.
41
101
369

22

142
12


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2,921


83.51


Grams.

408.
94
224
99
672
23
320


1,840


Gras.




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96.2


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91.6


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5361


95.9


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1,797



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88
103
1,040
99
291
109
800
37
320
2


7.57
.26
44.00
.75
7.26
1.60
18.24
.31
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.32


47
2
275
5
45
10
114
2
2"


41
101
363

22

14
12
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402
94
224
99
672
23
320
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4,
4
596
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......... 2,889 80.31 502 553 1,834 85 ,

140 105 6.97 44 20 41 35
5,837 ......... 71.68 .................. ...... ....... '.,

......... 2,784 73.34 458 533 1,793 90 .;I


364
120
8,000
100
320
120
1,200
40
320
800


130
7,233


96.4


91.3


91.2


96.4


- II I- I i


88
103
1,031
99
291
109
800
.37
320.
2

2,880


7.57
.26
45.60
.75
7.26
1.60
18.24
.31

1.32

81.91


47
2
285
5
45
10
114
2

2


41
101
357

' 22

14
12


97.8


389
94
224
99
672
23
320
..........


1,821


I I; K II


96
.........


6.40
70.43


40


18
=. =. .


38
..........


a 58.8


....... 4
6.
1.
I

........
M..'-.


34


S ... ...
. ... ...::i
.. .......*.


... .. .

.* ." .. ,

.. ':. ::


.....784. 75.51 472 9 1,783 ,8
-I 1-,l=


96.7


92.2


92.2


96.7


97.9


63.0


S ... .. ...


Labor-
atory
num-
ber.


449
486
481
480
482
485
484
483


449
486
494
480
482
485
484
483


- ------


sa


----------
.. .. .









13

throughout this experiment the urine was collected in portions cor-
ponding to eight-hour intervals. The results for the first period
Follow:

.IhA a 4.-Amount of nitrogen eliminated in the urine (digestion experiment No. 206).

8 a. m. 4 p. m. 12 p. m.
Period. to to to Total.
4 p. m. 12 p. m. 8 a. m.

n dsay: r
S eigatof urine .......... ..........................grams..- 50 710 602 1,862
Weght of nitrogen................................do.... 6.05 6.82 6.42 18.29
Percent of nitrogen................... ................ 1.10 .96 .90 ..........
menond day:
Weight of urine ..................................grams.. 1,112 688 417 2,217
Weightof nitrogen.................................do.... 6.34 6.26 4.63 17.23
Proent of nitrogen .................................... .57 .91 1.11.........
S hit day:
S W of urine.................................grams.. 508 688 357 1,548
ght of nitrogen............................do.... 5.54 6.76 4.68 16.98
Per cent of nitrogen..................................... 1.09 .99 1.31.........
i si rth day:
Weight of urine ............... ............... grams.. 385 633 375 1,393
Weight of nitrogen.............................do.... 5.54 7.22 4.99 17.75
Pe cent of nitrogen .................................. 1.44 1.14 1.33.........


Mhei -e quantity of urine eliminated and its nitrogen content during
I the second or work period are shown in the following table:

TABLE 5.-Amount of nitrogen eliminated in the urine (digestion experiment No. 207).

8 a.m. 4 p.m. 12 p. m.
Period. to to to Total.
4 p.m. 12 p.m. 8 a. m.

Plaot day:
Weight of urine................................grams.. 358 567 365 1,290
Weight of nitrogen...............................do.... 5.76 6.46 5.04 17.26
SPer cent of nitrogen ...................................... 1.61 1.14 1.38..........
i Second day:
Weight of urine ................ ..............grams.. 430 593 313 1,336
Weight of nitrogen ................................ do.... 5.98 7.18 4.41 17.57
Per cent of nitrogen ...................................... 1.39 1.21 1.41.........
Third day:
Weight of urine .................................. grams.. 503 625 395 1,523
Weight of nitrogen .................................do.... 6.29 7.00 5.41 18.70
S Per cent of nitrogen ..................... ...... ..... 1.25 1.12 1.37.........
Fourth day:
Weight of urine ..................................grams.. 850 469 369 1,688
Weight of nitrogen................................. do.... 6.72 6.52 4.91 18.15
Per cent of nitrogen ...................................... .79 1.39 1.33.........










... .... ..
"Hi

Ai...:ii!" :. :.":


'4' 4.: : : .
..-- EEE : :: .
i ... :iii ::'.' H.








14 9

During the third period, which was, like the first, a period of r
amount of urine eliminated and its nitrogen content were as foli

TABLE 6.-Amount of nitrogen eliminated in the urine (digestion experiment No. 90

8 a. m. 4 p.m. 12 p. m.
Period. to to to i:
4p.m. 12 p.m. 8 a.m. ."

First day:
Weight of urine...............................grams. 567 942 463
Weight of nitrogen................................do.... 6.41 6.78 4.68
Per cent of nitrogen .................................... 1.13 .72 1. .:.. :..
Second day:
Weight of urine............................... grams.. 635 543 4965 *-
Weight of nitrogen ............................... do... 5.52 6.46 5.10 i
Per cent of nitrogen ....................................... .87 1.19 1.a .:.. ... ....
Third day:
Weightof urine................................grams.. 568 663 642 : 1,7 4
Weight of nitrogen ...............................do.... 5.68 6.90 5.42 1. 0 ,
Per cent of nitrogen ................................ 1.00 1.04 1.00 ......-
Fourth day:
Weight of urine.................................grams. 658 688 474 1
Weight of nitrogen................................do... 5.81 6.60 5.12 I i
Per cent of nitrogen ........... .......................... .89 .96 ..08 .... ..

The above data regarding the income of nitrogen in the food andte :
excretion of nitrogen in the urine and feces served for computing' ::: t
.. = ....:... ..
average balance of the income and outgo of this element.* The effect.' i
of muscular work on the excretion of nitrogen is discussed when the ":i
experiments are considered as a whole. The nitrogen balance follows: iii
.. ".ji'. ..."
TABLE 7.-Daily income and outgo of nitrogen in experiment No. 17.

Nitrogen. ..
Periods. Time.. --- -__!
In food. In feces. In urine. Gain. :

Days. Grams. Grams. Grams. Grams.
First period, rest ............. .................. .. 4 20.88 1.75 17.56 1.57
Second period, work ............. ................ 4 20.08 1.74 17.92 .45
Third period, rest ............................... 4 20.48 1.60 17.61 1'

EXPERIMENT NO. 18. .

This experiment was carried on at the same time as .experiment No. fiS!
17. The subject, a chemist, 23 years of age, was in normal health..
During the first and third periods of the experiment little or no external :...






Subject.-Chemist B, 23 years of age.
Weight (without clothing).-At the beginning of the experiment, 55.2 kilograms.
(121 pounds); at the end of the first period and the beginning of the suecondb periodd'!:
56.1 kilograms (123) pounds); at the end of the second and the beginning ot'f h :,;
third period, 56.4 kilograms (124 pounds); at the close of the experiment, 56.6 kidIo'1Fi
grams (124& pounds).
Duration.-The experiment began with breakfast December 9, and the first peioi
continued four days. The second period began with breakfast December 3 and con ,
tinued four days. The third period began with breakfast December 17 and contini ei
four days.










15


TABLK 8.-Reults of experiment No. 18.


449
i"F 4WI
481
482

485
S,


=. ... i


Weight
of ma-
terial.


Grams.
606
120
6,000
100
820
120
1,000
120
400
400


Total
organic
matter.


Grams.
147
103
804
99
291
109
667
111
400
1


Nitro-
gen.


Grams.
12.60
.26
35.40
.75
7.26
1.60
15.20
.94

.16


Protein.


Grams.
79
2
221
5
45
10
95
6
1i"


Fat.


Grams.
68
101
277

22

12
37


Carbohy- Ah.
rates. As


0Grams.

306
94
224
99
560
68
400
..........


Gramns.
6
4
43
6
1
9
4

****-/*--


Heat of
com bus-
tion
calcu-
lated.





Calories.


Food materials.


FPlaT PERIOD
(RZBT).
Deseton experi-
ment No. S09.

EiggsL ..............
Butter...........
Milk............
Gelatin..........
Oatmeal.........
Bice..............
Bread ............
Potato chips......

Coffee ............
Total .......

Feces(water-free)
Urine.............

Amount digested.

Co effcients of di-
gestibility (per
cent) ..........
,SECOND PERIOD
(WORK).
Digestion experi-
ment No. S10.

Eggs..............
Butter............
Milk .............
Gelatin.............
Oatmeal ........
Rice..............
Bread ............
Potato chips......
Sugar.............
Coffee ............

Total..--.-.

Feces (water-free)
Urine.........---..
Amount digested.
Coefficients of di-
gestibility (per
cent)..........
THIRD PERIOD
I(REST).
Digestion experi-
ment No. 11.

ggs.............
Butter............
Milk.............
Gelatin...........
Oatmeal .........
Rice..............
Bread ............
Potato chips......
SuLgar.............
Coffee............

Total .......

Feees(water-free)
Urine.............

Aa.ount digested.
Ieffe ients of dl-
:eSStibiity (per
. o-0 t).........


96.4 91.4


91.5


94.1


98.4


67. 1


93.0


: : ...
Ia; :4 c.


li .i :.:.


......... 2,732- 74.17 464 517 1,751 73 14,749

121 97 6.03 37 31 29 24 503
4,981........ 52.02 ......... ................. ......... 534
......... 2,635 68.14 427 486 1,722 49 13,712


......... 96.5 91.9 92.0 94.0 98.3 67.1 93.0





606 147 12.60 79 68 .......... 6 ........
120 103 .26 2 101 .......... 4 ........
6,000 780 33.00 206 273 301 44 .........
100 99 .75 5 ......... 94 ........ ........
320 291 7.26 45 22 224 6.........
120 109 r 1.60 10 ......... 99 1 .........
1,000 667 15.20 95 12 560 9 .........
120 111 .94 6 37 68 4 .........
400 400 ........... .................. 400 ......... .........
400 1 .16 1 ......... ................... ......

......... 2,708 71.77 449 513 1,746 74 14,605

122 98 6.05 38 31 29 24 531
4,383 ......... 57.12 .................. .................514
......... 2,610 65.72 411 482 1,717 | 50 13,560


..... 96.4 91.6 91.5 94.0 98.3 67.6 92.9





606 147 12.60 79 68 .......... 6 ........
120 103 .26 2 101 .......... 4 ........
6,000 773 34.20 214 268 291 49 ........
100 99 .75 5 ......... 94 ..................
320 291 7.26 45 22 224 6 ........
120 109 1.60 10 ......... 99 1 .......
1,000 667 15.20 95 12 560 9 ........
120 111 .94 6 37 68 4 ........
400 400 ........... ................. 400..............
400 1 .16 1................... ........
......... 2,701 72.97 457 508 1 1,736 79 14,561

123 97. 6.27 39 30 28 26 503
5,068 ........ 56.70 ... ...................... ..... 522
......... 2,604 66.70 418 478 1,708 53 13,536
1 ,0 3,-- .


449
.486

480
482
486
484
488




496


'44

499


I













As in the preceding experiment, the urine was collected i.-

periods in portions corresponding to eight-hour intervals,

for the urine in the first period follows: ...


TAnBL 9.-Amount of nitrogen eliminated in the urine (digtion experiment Ai


Period.


First day:
Weight of urine................... ..........gram..
Weight of nitrogen ................................do....
Per cent of nitrogen ......................................
Second day:
Weight of urine............................ .....grams..
Weight of nitrogen.......................d.......................
Per cent of nitrogen ....................................
Third day:
Weight of urine..................................grams..
Weight of nitrogen ....................... ........do....
Per cent of nitrogen .....................................
Fourth day:
Weight of urine..................................grams..
Weight of nitrogen ...............................do....
Per cent of nitrogen ....................................


8a.m.
to
4 p.m.


4 p. m.
to
12p. m.


Isto
8 pa..


I-------- I -


530
4.24
.80

908
5.81
.64

478
4.06
.85

574
5.51
.96


- 6

1.80

562
4.86
.83

281
3.96
1.41

338
4.83
1.48


' ..
11 ..


.r.


.SE. .:..


.. :di V.


.... .. -.
.: .

The total amount of urine and its nitrogen content eliminated d

the second or work period follows:" 'i

TBLE 1.-Amoun of nitogen eliminate n the urine (dige....ion .pr
TABLE lO.--Amount of nitrogen eliminated in the urine (digestion expe intlybJ:!:


Period.


First day:
Weight of urine ..............................grams..
Weight of nitrogen................................ do....
Per cent of nitrogen ......................................
Second day:
Weight of urine...............................grams..i
Weight of nitrogen .................................do.. ..
Per cent of nitrogen ................................... i
Third day:
Weight of urine.................................grams..
Weight of nitrogen....................do.......do
Per cent of nitrogen...................................
Fourth day:
Weight of urine............ ............... grams..
Weight of nitrogen................................ do...
Per cent of nitrogen .................... ............


8 a. m.
to
4 p. m.


510
5.46
1.07

545
5.67
1.04

532
5.91
1.11

575
6.15
1.07


4 p. m.
to
12 p. m.


12 p. m.
to
8 La. m.


I I I -


380
5.66
1.49

259
4.20
1.62

295
4.48
1.52

486
5.14
1.18


ISO
3.14
1.6 6

281
M.88
L$4


1.754

196Is

L TD


--
. .. ."..





. ....:.- ..:


....... .. 1.
- .. ..' : < .....


:IC"
.....l.....i

":i$!!::



.'E:. .
":. : .."




.. ..rii' :t A


.li
.i;


S.* ..
.. .:... ... .':,.
:. ... *:.::..

"""i:'i
.** ..... : ..
.. .....M -....










he third period like the first was a period of rest. The urine
ated in periods corresponding to eight-hour intervals, and its
gen content, is shown in the following table:

TArms 11.-Amount of nitrogen eliminated in the urine (digestion experiment No. 11 ).

8 a. m. 4 p. m. 12 p. m.
Period. to to to Total.
4 p. m. 12 p. m. 8 a. m.

SWe eight of urine................................grams.., 503 563 285 1,351
:;': Weight of nitrogen......... .....do....I 5.68 5.24 3.79 14.71
Per cent of nitrogen................................. 1.13 .93 1.33 ........
W*ght of urine................................grams.. 723 367 242 1,332
Weight of nitrogen............................do .... 5.49 4.84 3.56 13.89
erc:,,:. ent of nitrogen. .................... ........... .76 1.32 1.47........
ti Weight of urine ................................grams.. 545 347 271 1,163
:::I- Weight of nitrogen.............................. do.... 5.45 4.55 3.98 13.98
Per ent of nitrogen .................................... 1.00 1.31 1.47........
oWeiht Of urine...............................grams.. 632 403 187 1,222
Wehtof nitrogen...............................do .... 5.69 5.08 3.35 14.12
Peaentof nitrogen..................................... .90 1.26 1.79..........


i From the data recorded above the balance of income and outgo of
nitrogen was determined. The results follow:

STABLE 12.-Daily income and outgo of nitrogen in experiment No. 18.


Period.
ii.:--

Firs t period, rest ...... ........... ..........-..
SSecond period, work ...............................
hird. period, rest. .........................
I.," __________


Nitrogen.
Time.
In food. In feces. In urine. Gain.

Days. Grams. Grams. Grams. Grams.
4 18.54 1.51 13.01 4.02
4 17.94 1.51 14.28 2.15
4 18.24 i 1.57 14.18 2.49


.... EXPERIMENT NO. 19.

;, This experiment was carried on with a student, C, age 22 years, and
| in good health. In the first and third periods as little muscular work
i was performed as possible. During the second period the subject
s made 80 trips up and down a hill. This was calculated to furnish
||1,471,080 foot-pounds, or 50,992 kilogrammeters, equivalent to a total
if 119 calories, or 30 calories per day.

SSubdject.-Student C, 22 years of age.
WaPleight (without clothing).-At the beginning of the experiment, 63.0 kilograms
I38 pounds); at the close of the first period, 62.7 kilograms (138 pounds). During
I second and third periods the weight remained unchanged.
.-The experiment began with, breakfast December 9; the first period
four days; the second began with breakfast December 13 and covered
ay.s; the third began with breakfast December 17 and covered only three days.
,' 132&---No. 117--02- 2


ra sl *'i* ..
- I.'


" ;; ...L .


















Food materials.


FIraT PERIOD
(RrET).
Digeabion experi-
ment No. 15.

Butter...........
Milk.............
Gelatin..........
Oatmeal .........
Rice.............
Bread ............
Potato chips......
Sugar............
Coffee ..........


Total.......


Peces(water-free)
Urine ............

Amount digested.

Coefficients of di-
gestibility (per
cent) ..........

SECOND PERIOD
(WORK).
Digestion experi-
ment No. 213.
Eggs..............
Butter...........
Milk.............
Gelatin...........
Oatmeal...........
Rice..............
Bread ............
Potato chips......
Sugar.............
Coffee ..........


Total .......


Feces( water-free)
Urine ..........

Amount digested.

Coefficients of di-
gestibility (per
cent) ...........

THIRD PERIOD
(REsT).
Digestion experi-
ment No. 214.
Eggs..............
Butter............
Milk..............
Gelatin...........
Oatmeal..........
Rice..............
Bread ...........
Potato eips......
Sugar.............
Coffee ............


Total.......


Feces( water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent)...........


Weight
of ma-
teral.


Grams.
619
120
6,000
100
320
120-
1,200
160
400
400


Total
organic
matter.


Grams.
125
103
804
99
291
109
800
147
400
1


111- fl


Nltro-
fge.


Grara
10.80
.26
35.40
.75
7.26
1.60
18.24
1.25
.1J


Grams.
67
2
221
6
45
10
114
8
1


Fati


Gambs.
568
101
277.

22
14'
49


GmaS


....g.. .





'9
4W(


* ,,::."


. .* 1
,, ,


... -
i





*--
a js*
":: .. :i
'1 "E: !. :


..... ,, .'i ;:
: ^ :':..:
:: .. :-s.^
: ::: i~


*I.L.*C i
,==,
- : C1


......... 2,879 75.72 473 5 21 1,85 .1

123 99 5. 36 o0 3
4,468 ......... 57.16 ......... ......... .......... .
S- m .................... ...
......... 2,780 69.95 437 491 1,882 1


......... 96.6 92.4 92.4 94.3 0.8 ..a


519
120
6,000
100
320
120
1,200
160
400
400


10.80
.26
33.00
.75
7.26
1.60
18.24
1.25

.16


67
2
206
5
45
10
114
8

1


273

224

14
49
........


58 .......
101 ..:.


301
94
224
99
672
96
400


4"?

S
1.
Iii.
S
a.-.~. .9


....... 2,85 7.32 458 517 1,880 7:

123 99 5.46 34 38 27 U
4,040 ......... 65.75 ......... ......... .......... .... ..

......... 2,756 67.86 424 479 1,8 "
I --= 1


389
90
4,500
75
240
90
900
120
300
300


96.5


94
76
580
74
219
82
600
111
300
* 1


92.6


92.6


92.7


SI: '1 .1 1I ._..


8.09
.20
25.65
.56
5.45
1.20
13.68
.94

.12


51
1
160
4
34
8
86
6

1


43
76
201



37


219
70
168
74
504
68


4L4....


4. .. *.


.. a .. .
3L
:: ,:::
.. ...


..-.... .
S~I*i


......... 2,137 55.89 351 383 1,4089: g

84 67 4.06 25 90 22 1
4,2465 ......... 50.31........ ......... .........

......... 2,070 51.83 326 363 1,381


.........


96.9


92.7


92.9


94.8


98.4


- .- -- _____________ I------------


:. .:':... .. 3
** ~ ~ .. *" ** i :;? :




aj.
..r 1 ...uf. ..l., ..
~~~~~~~~i : ==================

::i:~ ~ ~ ~~~~i ::,:: :!!: ii,,
:" :... :m.. .. .. .. :::..;I ... :# m : ;. :.
.... .......... .. : "":I.. : i ::m i :,.i. :.: .


Labora-
tory
num-
ber.


449
486
481
480
482
485
484
AU%


449
486
499
480
482
485
484
483


I I I I I I I 0


,:mjuu


proan


98.6


1 ......
. ......


- i;















e content being determined. Results from the first (rest)
bi follow:

14.t-Armount of nitrogen eliminated in the urine (digestion experiment No. 212)



4p.m. 12 p.m. 8a.m.


r.Be................................... grams.. 447 330 344 1121
ioin of nitrogen ................................do.... 5.46 5.68 4.20 15.33
nitrogen ...................................... 1.22 1.72 1.22..........
rine...............................grams.. 575 557 246 1,378
tIof niatrgen .................................do.... 6.10 4.01 3.57 13.68
e atof nitrogen ............... ...................1.06 .72 1.45 .........
of ne.............................. grams.. 275 5=3 203 811
.. of nitrogen .................... 10 5.56 3.19 12.85
.'f ..tofnitrogen ........ ....................... 1.49 1.67 1.57 ........
..... rine...................................grams.. 358 500 30 1,158
:%i of mine............grams 358 500 300 1,158
Wib tRof nitrogen..............................do.... 5.48 6.40 3.42 15.30
iie.: est ot nitrogen .............. 1.53 1.28 1.14 ..........


7The amount of urine eliminated during the second (work) period
ad -ito nitrogen content was as follows:

T piI,5.-Amount of nitrogen eliminated in the urine (digestion experiment No. 218).

8 a. m. 4 p. m. 12 p. m.
Period. to to to Total.
S4p.m. 12 p.m. 8 a. m.


Wegtt of urine .................................grams.. 385 311 280 976
SW*htof nitrogen ................................ do.... 5.27 5.22 4.82 15.31
er cent of nitrogen.................................... 1.37 1.68 1.72 .........
tof irine .................................. grams.. 337 345 203 885
SW t ghtof nitrogen ...................................do.... 5.66 6.83 3.53 16.02
i ent of nitrogen....................................... 1.68 1.98 1.74 ..........
*W ht ofurine................................. grams.. 367 378 263 1,008
Weight of nitrogen .............................do.... 6.17 6.35 4.63 17.15
r cent of nitrogen..................................... 1.68 1.68 1.76.........
r Weightof urine ............................... grams.. 507 387 277 1,171
Weight of nitrogen ................................do.... 6.54 5.61 5.12 17.27
centof nitrogen........................................ 1. 1. 1.85..........























.." ....... .. ..... ....


... .. ... .. ..




....... : .... "..... ...





The details of the elimination of nitrogen during theth
period, which covered only three days, are given in the
table:

TABLE 16.-Amount of nitrogen eliminated in the uine (digestion experiment ..m

8 a. m. 4 p. m. 12 p. a
Period. to to to
4 p. m. 12 p.m. 8. '. :

First day:
Weight of urine .................................grams.. 82 6568 A
Weight of nitrogen.............................. .do.... 6.77 6 .1 5 .2
Per cent of nitrogen ................................... .. 1.51 .99 1.3
Second day:
Weight of urine ..................................grams.. 535 443 .i
Weight of nitrogen.................................do.... 5.89 6.42 4.
Per cent of nitrogen ...................................... 1.10 1.45 1. .
Third day: :.:
Weight of urine ............................... grims.., 450 581 4 a -
Weight of nitrogen ................ ......... ....do..... 5.76 6.21 4.i44 :::
Per cent of nitrogen ...................................... 1.28 1.17 ,97 .


The nitrogen balance was as follows: :

TABLE 17.-Daily income and outgo of nitrogen in experiment No. 1 9. "

Nitrogen..
Periods. Time. ... ..
In food. In feces. In urine. (i asin

Days. Grams. Grams. GramNs.I
First period, rest ............................ 4 18.93 1.44 I2m 9:p..W
Second period, work .............. .................. 4 18.33 1.37 16.44
Third period. rest..................... ............. 3 18.63 1.35 .77 .

EXPERIMENT NO. 20.
.: .. :.:. .^ '

This experiment began a second set with the same subjects as in
experiments Nos. 17, 18, and 19. In this set the diet in the first and
third periods contained less than the normal amount of protein a4I
energy, and during these periods little, if any, muscular work a'
performed. In the second period considerable muscular work was pb&
formed and the energy value of the diet was increased until it-s5i
equal in this respect to a normal diet. During the second period UhQ
subject of experiment No. 20 made the trip up and down-hill fiftiy-tl
times. This, according to the method of calculation followed, gv, e
1,136,356 foot-pounds, or 49,421 kilogrammeters, equivalent to 9: j
calories, or 23 calories per day.
Subject.-Cheniist A, 30 years of age.
Weight (without clothing).-At the beginning of the experiment 69.8 ki
(153.5 pounds); at the end of the first period 68.6 kilograms (151 pounds).
the second and third period the weight did not change. .
Duraton.-The experiment began with breakfast March 8, the first periodic
four days. The second period began with breakfast March 12, and covered four
The third period began with breakfast March 16, and covered four days.


." .. .. .. .. .:. .....::.:::..:::..::...!ii,







21

21


TABLE 18.-Results of e.pjeriment No. S0.


4.0


800;' :i=
j'...:* 607i y .
,I '. i.-


Weight
of ma-
terial.


Grams.
364
40
8,000
100
820
120
840
40
240
800


Total
organic
matter.


Grams.
88
36
1,042
99
288
109
565
37
240
2


Nitro-
gen.


Food materials.



FIRST PERIOD
(REST).
Digtion experi-
meant No. 16.

1gg. .............
Butter............
Milk.............
Gelatin.........
Oatmeal.........
Rie ..............
Bread ..........
Potato chips......
Braar.............
Coffee............
Total .......

Feces (water-free)
Urine............

Amount digested.

Coeffcients of di-
gestibility (per
cent)..........

SECOND PERIOD
(WORK).
Digestion ezperi-
meta No. 16.
Eggs.............
Butter............
Milk...........
Gelatin...........
Oatmeal .........
Rice ............
Bread ..........
Potato chips......
LSUar.............
wfee ............

Total.......

Pieces (water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ..........

THIRD PERIOD
(REST).
Digestion ezperi-
meat No. 217.
Eggs............
Butter............
Milk............
Gelatin ..........
Oatmeal........
Rice.............
Bread ...........
Potato chips......
Suar.............
Coffee ............

-Total......

Feces (water-free)
Urine............

Amount digested.

Coefficients of di-
getibility (per
cent) ...........


Protein.


Grams.
47
1
290
5
49
10
79
3
2


Fat.


Grams.
41
35
378
23
...... ii"
11
15


Carbohy-
drates.


Grams.

..........
94
216
99
475
19
240
..........


Ash.


Grams.
4
1
64

6
1
8
2


Heat of
corn bus.
tion
calcu-
lated.


-Ioo...o..

.........
o... ...

.....:...


......... 2,506 77.74 486 503 1,517 86 13,769

128 92 6.09 38 29 25 36 477
6,705 ......... 71.90 ......... ......... .......... ......... 560

......... 2,414 71.65 448 474 1,492 50 12,732


......... 96.3 92.2 92.2 94.2 98.4 58.1 92.5





364 88 7.57 47 41 .......... 4 .........
180 160 .43 3 157 .......... 5........
7,408 963 41.48 259 367 337 / 56........
100 99 .75 5 ......... 94........ ......
820 288 7.84 49 23 216 6 ........
120 109 1.60 10 ......... 99 1 ........
1,000 672 15.10 94 12 566 10 ........
100 92 1.20 7 37 48 4 ........
420 420 ........................... 420................
800 2 .32 2 ......... .......... ......... .........

......... 2,893 76.29 476 637 1,780 86 16,063

130 98 6.34 40 29 29 32 531
3,858 ........ 66.99 ......................... ...... ...... 545

......... 2,795 69.95 436 608 1,751 54 14,987


......... 96.6 91.7 91.6 95.5 98.4 62.8 93.3





364 88 7.57 47 41 .......... 4 .........
40 36 .10 1 35 .......... 1.........
8,000 1,063 44.80 280 395 388 60.........
100 99 .75 5 ......... 94..............
320 288 7.84 49 23 216 6.........
120 109 1.60 10 ......... 99 1 ........
840 565 12.68 79 11 475 8 ........
40 37 .48 3 15 19 2 ........
240 240 ......... ....... ......... 240..................
800 2 .32 2 ................... ................

......... 2,527 76.14 476 520 1,531 82 13,981

130 95 6.50 41 25 29 35 493
6,971 ......... '69.80 ............ ................ ......... 544
......... 2,432 69.64' 435 496 1,502 47 12,894


96.2 91.6 91.4 96.2 98.1 57.3 92.6


Grams.
7.57
.10
46.40
.75
7.84
1.60
12.68
.48

.32


449
506
515.
480

506
185
507





516


449
508
520
5M0
480
505
485
507
*506


i l.
..O21


96.2


91.5


91.4


95.2


98.1


57.3


3.6


". ..;. .
: ..]..."
i .!.k ,, ': ''
f .,,.:::'..:* .... .: :.. .: .. .














oI experiment x o. u me t o ue iat was ., aVu grams ana i.:
content 0.96 per cent, or 18.1 grams; on the second yda.y .I
with a nitrogemncontent of 1.02 per cenit, or 17.9 grams on
day 1,645 grams, with a nitrogen content of 1A.1 per
grams; and on the fourth day 1,420 grams, with a nitrogen
1.22 per cent, or 17.3 grams. The total nitrogen eliminated iii:
fore 73.9 grains.
During the second (work) period the urine was collected
corresponding to eight-hour intervals. The results follow.; .:

TABLE 19.-Amount of nitrogen eliminated in the urine (digestion eperimetW
.... .i : .. ..: : .....liii ..

8 a.m. 4 p.. 12.gS P I
Period. to to to. .. 4
4 p. m. 12 p. m. 8 i. "

First day:
Weight of urine .................................grams.. 345 03
Weight of nitrogen.................................do.... 5.00 5.48 .1
Per cent of nitrogen ........... .................... 1.45 1.81 L:
Second day: :!::.
Weight of urine ...............-...- ...........grams. 305 5
Weight of nitrogen......... .......................do.... 4.70 7.17 4.
Per cent of nitrogen ....................................... 1.54 2.03 1:U 4A
Third day:.
Weight of urine ................................grams.. 282 281 2,9::
Weight of nitrogen...............................do... 5.16 5.99 & .:
Per cent of nitrogen ............. ..................... 1.83 2.13 1. l.:
Fourth day: '
Weight ofurine ................................grams.. 358 350. 4 ::,i
Weight of nitrogen........................... ..... do... 6.19 5.99 .8 '::
Per cent of nitrogen .................................... 1.73 1 71 t..d .


During the third (rest) period the urine was also collected is i
tions corresponding to eight-hour intervals. The amount of urinii
..' .i.:
its nitrogen content are shown in Table 20, which follows:

TABLE 20.-Amount of nitrogen eliminated in the urine (digestion experiment N oii


8 a.m. 4 p.m. 12 p.. ; :
Period. to to to :
4 p. m. 12 p. m. 8 .m...

First day:
Weight of urine ............................grams.. 448 1,005 43
Weight of nitrogen...............................do... 5.82 6.53 5.16
Per cent of nitrogen................................... 1.30 .66 l.
Second day:
Weight of urine ............................... grams.. 725 618 81. :
Weight of nitrogen...............................do... 6.53 6.26 ~ 4.8
Per cent of nitrogen ................................ .90 1.02 1.279.
Third day:
Weight of urine ................................grams. 770 ,645 42
Weight of nitrogen.............................. do... 6.62 6.39 5.02
Per cent of nitrogen ...................................... .86 .99 L.- .
Fourth day:
Weight of urine ..................................grams. 397 794 298 .
Weight of nitrogen................................do... 5.56 8.58 2.50
Per cent of nitrogen ..................................... 1.40 1.08 ..
4 L


*m '
... .:.* ..: :.!





:: ... .. .
.:...... .



............ ..:





1pi
..l .U ..

....... .. ..:..
28

wtFrom the data given in the preceding tables the balance of income
o utgo of nitrogen was calculated as follows:

i" "TABLz 21.-Daily income and outgo of nitrogen in experiment No. 20.

S. ..Nitrogen.
Periods. Time. Gain (+)
In food. In feoe. In urine. or
loss (-).

t .Days. Grams. Grams. Grams. Grams.
Fip od, rest .................................... 4 19.43 1.62 17.98 -0.07
pbd period, work .............................. 4 19.07 1.59 16.75 + .73
1b period, ret................................... 4 19.04 1.62 17.45 .08


EXPERIMENT NO. 21.

h:i':e experimental conditions were the same as in the preceding
:: ;4:x:periment. The subject, a chemist, was 23 years of age and in good
Health. During the work period the subject made the trip up and
IEIdown ill"68 times. This was calculated to yield 1,223,235 foot-pounds,
S or 42,422 kilogrammeters, equivalent to 99 calories, or 25 calories per
&::day. X3he results of the digestion experiment follow:
;. ~bjyed.-Chemist B, 23 years of age.
i: Weight (without clothing).-At the beginning of the experiment, 56.4 kilograms (124
pounds); at the end of the first period and the beginning of the second period, 55.9
i:.i: kilograms (123 pounds); at the end of the second and the beginning of the third
period, 56.4 kilograms (124 pounds); at the.end of the experiment, 56.1 kilograms
S (128 pounds).
S Duration.-The periods each covered four days and began with breakfast March 8,
S 12, and 16, respectively.
:.: .. .. .


"Nt...."......, .. ...
::: .: : : .....,:. i, :,. :j,.% ::,.,;':::;..: .. .. .
." ***.. ...,.. _.. + .... .........


wEM





.. ... ..... .. ... .....


24 -
: "" "" "o .. N o R :r
.. ;-;, ... = *,:

TABLE 22.-Beadl of ex.uiment No. l. ,
- ..-- _^ ** '*- .- i


Food materials.


Weight
of ma-
terial.


Total
organic
matter.


Nitro-
gen.


Protein.


fat.


Carbohy
dates.


T I I --T 1 1 I. I


FIBnr PERIOD
(RBST).
Wigestion experi-
ment No. 18.

Eggs..............
Butter............
Milk.............
Gelatin...........
Oatmeal.........
Rice............
Bread ............
Potato chips......
Sugar............
Coffee............

Total ........

Feces (water-free)
Urine............

Amount digested.

Coefficients of di-
gestibility (per
cent) .........

SECOND PERIOD
(WORK).
Digestion experi-
ment No. 819.
Eggs .............
Butter............
Milk............
Gelatin...........
Oatmeal ........
Rice.............
Bread ............
Potato chips......
Sugar.............
Coffee ............

Total.......

Feces (water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent). ........

THIRD PERIOD
(REST).
Digestion experi-
ment No. fS0.
Eggs.............
Butter...........
Milk .............
Gelatin..........
Oatmeal.........
Rice .............
Bread ...........
Potato chips......
Sugar ............
Coffee ..........

Total .......

Feces (water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ...........


Grams.
608
40
6,000
100
320
120
640
120
320
400


115
4,497


Grams.
147
36
781
99
288
109
430
110
320
1


Grams.
12.65
.10
34.80
.75
7.84
1.60
9.66
1.44
......16


Grams.
79
1
218
5
49
10
60
9

i"


Grams.
68
35
288

234

84
44


Grams.

280
94
216
99
362
57
320
..........


AI.


: ..:.M


-..... .. .

.....-...,..


......... 2,321 69.00 432 461 1,4 28 _"


88
=.......


5.75
48.89 ..


36


I I I b- I: I: --' --- I *---


2,233


63.25


1,411


. 47


________________ I I 1 I: 1 l I


608
180
5,408
100
320
120
800
180
500
400


96.2


91.7


12.65
.43
30.28
.75
7.84
1.60
12.08
2.16

.16


91.7


3
189
5
49
10
75
14
.......


92.4


68
157
268

23

10
66


98.8


246.
94
216
99
452
86
500
..........


64-.4


if
= = = = = I .- s


6
6
41


1
8
8


..- .
... ....-.- 'ii
.. ::... ,: !
.. .-,... ":. .
... ..". 'ii .



.... .." ;.:.;. :.;.

I: p:,i i,!


......... 2,710 67.95 425 592 1,693 76

111 87 5.41 34 37 16 25 *
4,061 1......... 54.90 ......... ......... .......... ........

......... 2,623 62.54 391 555 1,677 50 14, I

96.8 92.0 92.0 3.8 99.1
......... 96.8 92.0 92.0 93.8 99.1 66.7 ,SA
4 _^ _^ ^ ^ _^ __ _= *_ __^ :


608
40
6,000
100
320
120
640
120
320
400


147
36
797
99
288
109
430
110
320
1


12.65
.10
33.60
.75
7.84
1.60
9.66
1.44

.16


79
I
210
5
49
10
60
9

1


68
35
296

23
- 8
44


291
94
216
99
362
57
320
...........


6
1
45

6
1
6
5


I


.. ..... .. ..






6- i k* & I
..::..:..
.. : '. .. "'i.

-:,.. E:"|.|
.. "'....-'g.
S- .'.i

-.! """.. .
""...." ...


......... 2337 67.80 424 474 1,439 70 I ..

114 87 5.62 35 33 19 27
4,624 ......... 54.65 ......... ......... .......... .... .....

2,250 62.18 389 441 1, 420 48 118
.. .. iI = '. .- ..


96.3 911 91.7 98.7 61.4


Labora-
tory
num-
ber.


-~I


96.3


91.7


91.7


98.0


98.7


61.4









'+ 25

.::On the first day of the first (rest) period 1,413 grams of urine was
inated, 'containing 0.72 per cent, or 10.2 grams nitrogen; on the
nd day, 1,137 grams urine, containing 1.03 per cent, or 11.7 grams
itrogen; on the third day, 943 grams urine, with 1.3 per cent, or 12.4
nitrogen; and on the fourth day, 1,004 grams urine, containing
1 05 per cent, or 14.6 grams nitrogen. The total nitrogen eliminated

as, therefore, 48.9 grams, or 12.2 grams per day.
:* ring the second (work) period the urine was collected in por-
.ions corresponding to eight-hour intervals and its nitrogen content
..termined. The details follow:

'tSAW 23.-Amount of nitrogen eliminated in the urine (digestion experiment No. 219).


Period.


Weight of urine ............................... grams..
Weight of nitrogen............................... do....
Per cent of nitrogen .....................................
Second day:
S Weight of urine................. ................. grams..
Weight of nitrogen................................do....
Per cent of nitrogen ....................................
Third day:
WeJght of urine..................................grams..
Weight of nitrogen....................... ...........do....
Per cent of nitrogen ....................................
Fourth day:
Weight of urine...................................grams..
Weight of nitrogen..............................do....
Per cent of nitrogen ....................................


8 a. m.
to
4 p. m.


568
5.45
.96
502
5.37
1.07
461
5.44
1.18
455
5.78
1.27


4 p. m.
to
12 p. m.


315
4.85
1.54
258
4.31
1.67
427
5.64
1.32
323
4.55
1.41


12 p. m.
to I Total.
8 a. m.


143 1,026
2.76 13.06
1.93 ..........
203 963


3.59
1.77
193
.3.45
1.79
213
3.71
1.74


13.27
..........
1,081
14.53

991
14.04
..........


Duigtetid(et eidteuiewsas olce npr


S During the third (rest) period the urine was also collected in por-
i: tions corresponding to eight-hour intervals. The results follow:

TABLE 24.-Amount of nitrogen eliminated in the urine (digestion experiment No. 220) .


S8 a. m.
Period. to
S.4 p. m.

i:::Flt day:
Weight of urine ................................grams.. 780
Weight of nitrogen...............................do.... 6.24
Per cent of nitrogen ..................................... .80
Second day:
Weight of urine .................................grams.. 578
S Weight of nitrogen...............................do ... 6.65
. Per cent of nitrogen ..................................... 1.15
..Third day:
Weight of urine ..................................grams.. 655
Weight of nitrogen.................. ................do.... 6.48
Per cent of nitrogen..................................... .99
Fourth day:
Weight of urine ................................. grams.. 503
Weight of nitrogen............................do.... 5.28
Per cent of nitrogen ..................................... 1.05


4 p. m. 12 p. m.
to to Total.
12 p. m. 8 a. m.


350
4.73
1.35
225
3.44
1.53
495
4.80
.97
280
4.42
1.58


173
2.73
1.58
197
3.31
1.68
251
4.02
1.60
137
2.55
1.86


1,303
13.70

1,000
13.40

1.401
15.30
..........
920
12.25
..........


ri''.: ..M.. "


` ` ` `


I I I


-


1-


I I


I























Firt period, rest .....................................
Second period, work..............................
Third period, rest ...................................


I 1 .1 ~ ;;C-


Dary.
4
4
4


17. 5
16.99
16.95


mA l
1........
alh *

- -- .".* .^*i lmilj
'*--^M
**'' *


EXPRIMEtNT NO. 22.


The experimental conditions were the same in this as i 1
preceding experiments. The subject was the same as in
No. 19. During the first and third periods the subject
little external muscular work as possible. During the a
a considerable amount of external muscular work was
This consisted in making 70 trips up and down a hill 140
The work expended in raising the body to the height of thei
calculated to yield 1,319,799 foot-pounds, or 45,421 kilo..
This is equivalent to a total of 106 calories, or an average of 4 'Q
per day. The details of the digestion experiment follow.

Subject.-Student C, 22 years of age. ..
Weight (without clothing).-At the beginning of the experiment, 65.5 dllog aiE .
pounds); at the end of the first period and the beginning of the second ip|q4
kilograms (141.5 pounds); at the close of the second and the beginning of tla ..
period, 65 kilograms (143 pounds); at the end of the experiment, 64.k8 Mib
(141.5 pounds). .. : i.::;:
Duration.-The experimental periods, each consisting of four days, b9eg
breakfast on March 8, 12, and 16, respectively.
NN .. ....... ..


.. ::::...
.....,..iii...


... ...: ; .. .,,


; :'::" 1
". ":: "ii




ME'
; ...... .






':. : i: i..
:. ....
H:.








.M.




:" A .:".





A:ii: :: :!!! ;.'? :: .. ... 4 7 .
:i ". .: ..
S ..... .,, .

27


TABLE 26.-Rerdt8 of experiment No. Be.


K *.- :,i I:""r :
r i i' I
-ag



-^-':: .:l'.

i :::,;:.::::; ,

. ".C


.:... .. .:


449
.,


Us
186

507
08


t8s


FtOd materials.



FIner PERIOD
(REUT).
DiEgesdan ca~pri-
meant No. Ml.

Egg .............
hltther...........
Milk..............
Gelatin...........
Oatmeal.........
Biem............
Bread............
Potatd chip ......
Ehiw .............
ee............

Total........

?ecIes (water-free'
Urine ............

Amount digested.

.Coefficients of di-
gestibility (per
cent) ...........


SBEoND PERIOD
(WoRK).
Dimgseion esperi-
ment .o. SSS.
Egga..............
Batter............
Milk..............
Gelatin..........
Oatmeal..........
Ricee.............
Bread .............
--Potato chips.....

Total.......
Total .......-


Feces (water-free)
Urine.............


Amount digested.

Coefficients of di-
gestibility (per
cent) ...........

THIRD PERIOD
(REsT).
Digestion experi-
met t No. SS.
Eggs..............
Butter...........
Milk.............
Gelatin.........
Oatmeal ........
Rice..........
Bread ...........
Potato chips......

.Ttal........
TW .......

Feces (water-free)
Urine...........

Amount digested.

Coef8ients of di-
gestibiluty (per
cent) ........


Weight
of ma-
terial.






Grams.
55666
40
6,000
100
320
120
840
160
320
400


Total
organic
matter.


Grams.
134
36
781
99
288
109
565
147
320
1


Nitro-
gen.


Gramm.
11.56
.10
34.80
.75
7.84
" 1.60
12.68
1.92

.16


Protein.


Grams.
72
1
218
5
49
10
79
12

1


Fat.


(Grams.
62
35
283

23

11
59


Carbohy-
drates.


Grams.
..........
280
94
216
99
475
76
320


Ash.


Heat of
combus-
tion.
calcu-
lated.


Urumns. i lories.
6 .......
48 .........
......... .........
1 .........


......... .........
......... .........


......... 2,480 71.41 447 473 1,560 77 13,446

118 88 5.32 33 36 19 25 457
5,838 ......... 56.94 ......... ......... .......... ......... 517

......... 2,392 66.09 414 437 1,541 52 12,472


......... 96.5 92.6 92.6 92.4 98.8 67. 5 92.8





556 134 11.56 72 62 .......... 6 I.........
180 160 .43 3 157 .......... 5 .........
5,408 703 30.28 189 268 246 41 ........
100 99 .75 5 ....... 94 ... ...........
320 288 7.84 49 23 216 6 .........
120 109 1.60 10 ......... 99 1......
1,000 672 15.10 94 12 566 10 .........
220 202 2.64 16 81 105 9 .........
500 500 ......................... 500...............
400 1 .16 1....................... .......

......... 2,868 70.36 439 603 1,826 78 15,726

114 92 5.23 33 41 18 22. 499
4,146 ......... 62.45 .....................................507

......... 2,776 65.13 406 562 1,808 56 14,720


......... 96.8 92.6 92.5 93.2 99.0 71.8 93.6





556 134 11.56 72 62 .......... 6.........
40 36 .10 1 35 .......... 1.........
6,000 797 33.60 210 296 291 45 .........
100 99 .75 5 ......... 94 ..................
320 288 7.84 49 23 216 6 .........
120 109 1.60 10 ......... 99 1........
840 565 12.68 79 11 475 8 .........
160 147 1.92 12 59 76 7 .........
320 320 ........ ......... ......... 320..................
400 1 .16 1......... .........................

......... 2,496 70.21 439 486 1,571 74 13,568

107 83 5.16 32 27 24 24 431
5,996 ......... 62.09 ......................................... 509

......... 2,413 65.05 407 459 1,547 50 12,628


96.7


92.6


92.7


94.4


98.5


67.6


93.1


......... ...




... ............
.:.. ..~u
....., ::.: .. .

...... .. .. .. ":" ... ..... .
.."
:: ." :E: .."E ." 1 ..


h ... ,....







.4
. :...:






ii |
:.... .. "* ,







.!#.. :::

"I, ..: .


480
fMO

5w0.

507
.* f


523


.... "'





.. .... ..

2 8 .. ........ .


In the first (rest) period of this experiment the urine wa:
in a single portion for each day. On the first day 952
excreted, containing 1.39 per cent, or 13.2 grams nitrogen; the-a
eliminated on the second day was 1,457 grams, with a nitrogen..
of 0.96 per cent, or 14 grams; on the third day 1,537 grams,
nitrogen content of 0.91 per cent, or 14 grams; and on the.
day 1,392 grams, containing 1.13 per cent, or 15.7. grams
The total nitrogen eliminated in the urine during the whoi:
was, therefore, 56.9 grams, or 14.2 grams per day. During
ond (work) period the urine was collected in portions correspo
to eight-hour intervals, and its nitrogen content determined.
results are shown in the following table:

TABLE 27.-Amount of nitrogen eliminated in the urine (digestion experiment &i. 40-

8a. m. 4 p. m. 12 p.m.
Period. to to to
4 p. m. 12 p. m. 8 a. m.i,.:.

First day:. ...
Weight of urine .................................grams.. 317 340 197 -
Weight of Pitrogen............... ...... ......... do .... 4.85 5.95 4.26 -
Per cent of nitrogen ...................................... 1.53 1.75 2.165 -...
Second day:
Weight of urine ...............................grams.. 335 260 256 8....
Weight of nitrogen...............................do.... 5.90 4.76 5.28 ,
Per cent of nitrogen ..................................... 1.76 1.83 2.0 .......
Third day: ..
Weight of urine .................................grams.. 417 343 291 1,
Weight of nitrogen.................................do.... 6.05 5.73 4.51
Per cent of nitrogen .................................... 1.45 1.67 1. .-......
Fourth day:
Weight of urine ...............................grams.. 712 409 270 .
Weight of nitrogen ...............................do.... 6.34 4.87 8.97 '
Per cent of nitrogen ..................................... .89 1.19 1.47 .... .
F u t d y .. .: .. ::!..
Weight ....

-- *


P.". :.:a....

... ....










..." :: q ...
.... .....

". E' .E :: "E:E :~








29

SDuring the third (rest) period the urine was as before collected in
rtions corresponding to eight-hour intervals. The amounts elimi-
eated and the nitrogen in it are shown in Table 28, which follows:

S 28.-Amount of nitrogen eliminated in the urine (digestion experiment No. 228).

P.e8-. a.m. 4p.m. 12 p.m.
Period. to to to Total.
"4 p.m. 12 p.m. 8a.m.

'tof urine ................................gams 532 639 457 1,628
Wi ght f nitrogen................. .......... 5.75 5.50 4.43 15.68
i.. e Ii elt of nitrogen ............................. ...... 1.08 .86 .97 ........
SM tof urine .................................grams.. 55 817 363 1,755
W *.t of nitrogen..........................do.... 4.95 6.54 4.10 15.59
StiOpla t Af nitrogen..................................... .86 80 1.13.........
ofuine ........................... grams.. 502 635 470 1,607
it'::, Lb .of nitrogen.......................... .do.... 5.77 470 5.55 16.02
l e t of nitrogen ............ .................... 1.15 .74 1.18 .........
Vu0 th day:
H. V o:lurit.. Of urine ...............................grams.. 365 369 272 1,006
Weigt of nitrogen........... ..............do.... 5.29 5.54 3.97 14.80
Per ent of nitrogen ................................. 1.45 1.0 1.46........


ai: ims s the case in the preceding experiments, the daily balance of
j n 4 j om. e and outgo of nitrogen was determined.

| TABLE 29.-Daily income and outgo of nitrogen in experiment No. 22.

I.., ..;:... Nitrogen.
Periods. Time.
In food. In feces. In urine. Gain.

Days. Grams. Grams. Grams. Grams.
; irst period. (rest) .................................. 4 17.85 1.33 14.24 2.28
L" Secod period (work)............................... 4 17.59 1.31 15.61 .67
'Thrid period (rest) ................................. 4 17.55 1.29 15.52 .74


EXPERIMENT NO. 23.

SThis experiment began the third series reported in the present pub-
:lication, which was made with the same young men who had served
as subjects of the preceding experiments. The diet contained less
protein and energy than normal and was unchanged during the second
or work period. Except in the second period, no appreciable amount of
Smtuscular work was performed. During the second period the subject
iOf experiment No. 20 made the trip uphill 55 times. This was calcu-
NHted to yield 1,201,915 foot-pounds, or 41,565 kilogrammeters, equiv-
salent to a total of 97 calories, or an average of 24 calories per day.
Thhe average results of the digestion experiment follow:

ultde-je .-Chemist A, age 30 years.
J- Weight withoutt clothing).-At the beginning of the experiment was 69.8 kilograms
l3.5 pounds); at the end of the first period and the beginning of the second
sod, 68.4 kilograms (150.5 pounds); at the close of the second and the beginning
.t.he third period, 67.7 kilograms (149 pounds); at the close of the experiment, 67.3
ams (148 pounds).
Durafion.-The three experimental periods, each of four days' duration, began with
t March 22, 26, and 30, respectively.



..
i E ': : ..i .. ... : .. [ .. ....-..
.. .
i!: ,.:,:::: i ,.,,,,... :: : .


........ ...
.i:=
;;;


I






NEN .. E" ": :" .. ... .. ............ .. .E. ........."... ."
.. ... .. '. : ..
.. .. ......
,0, 4.... ..

.. .. .. .. ... ... i i
T ABLE. :':i.: :" .. *SM nh:..
TABLE 30.-ReauL tt I. fic p ...-... c
"" *'. ,, "* .: "*


Food materials.


449
528
525
480
505
485
627
526




531











449
528
535
480
505
485
527
526




536


Amount digested. ..


Coefficients of di-
gestibility (per
cent) ...........


Weight
of ma-
terial.


Total
organic
matter.


Nitro-
gen,


Protein.


Pat.


- I---- I----l -t----l I- 1"" "f


Grams.
364
80
7,600
100
.280
120
900
S 40
320
800


Grams.
88
70
966
99
252
109
604
36
320
2


Orwams.
7.57
.24
41.80
.75
6.86
1.60
14.31
.50

.32


Grams.
47
2
261
5
48
10
90
3

2"


Grams.
41
68
358

20

11
13
i.. .


FIRST PERIOD
(REST).
Digestion experi-
ment No. 24.

Eggs .............
Butter............
Milk.............
Gelatin.........
Oatmeal........
Rice.............
Bread .........
Potato chips......
Sugar.............
Coffee ............

Total........

Feces(water-free)
Urine............

Amount digested.

Coefficients of di-
gestibility (per
cent) ...........
SECOND PERIOD
(WORK).
Digestion experi-
ment No. 25.
Eggs............
Butter...........
Milk..............
Gelatin .........
Oatmeal.........
Rice.............
Bread ............
Potato chips......
Sugar.............
Coffee ...........

Total........

Feces(water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ...........

THIRD PERIOD
(REST).
Digestion experi-
ment No. le6.
Eggs.............
Butter...........
Milk.............
Gelatin..........
Oatmeal........
Rice .............
Bread .............
Potato chips......
Sugar............
Coffee ..........

Total........

Feces (water-free)
Urine.............


364
80
7,600
100
280
120
900
40
320
800


7.57
.24
41.04
.75
6.86
1.60
14.31
.50

.32


47
2
257
5
43
10
90.
3
2


41
68
353

20
......ii.
11
13


......... 2,556 73.19 459 506 1,591 I

118 87 5.82 36 24 27 .
4,274 ......... 62.87 ......... ......... .......... ..

......... 2,469 67.37 423 482 1,564


......... 96.6 92.0 92.2 95.3 98.3 8I





364 88 7.57 47 41 .......... -:
80 70 .24 2 68 ..........
7,600 1,005 41.04 257 581 367 41
100 99 .75 5 ....... 94
280 252 6.86 43 20 189 i
120 109 1.60 10 "........ 99 .
900 604 14.31 90 11 508 .
40 36 .50 8 1 20
320 320 ......... .. ........20. .
800 2 .32 2 ......... ..........,

......... 2,585 73.19 459 534 1,592 S

121 88 5.88 37 26 25
5,988 ......... 68.35 ......... .......... .. .
-....... .... .... ...^ ....


2,497


9


6.6


67.31


92.0


91.9


96.1


I i.I .


.. .. .....;
... .. .. .' ,: :
,'",. ,",
,.... ... ,..... .::,. ::.. ..: ",,,,: : -.
.. .::.*. ::: ... .:. .... : .!


Labora-
tory
num-
ber.


......... 2,546 73.95 463 506 1,577.

117 85 5.74 36 21 28
6,533 ......... 66.75 ......... ... ...............i

......... 2,461 68.21 427 -" 485 1,4


....... 96.7 92.2 92.2 95.9 9 S..2 -


449
528
540
480
505
485
527
526




541


~_




...:. ...


..... .. ...
.. ..;;. .
81


Puing the first (rest) period of this set of experiments the urine
collected in a single portion for each day. On the first day the
i.. a ount of urine eliminated was 1,405 grams, its nitrogen con-.
L25 per cent, or 17.6 grams; on the second day, 1,913 grams
Ss n :e training 0.86 per cent, or-16.4 grams; on the third day, 1,118
urine, containing 1.39 per cent, or 15.5 grams; and on the
day, 9,097 grams urine, containing 0.82 per cent, or 17.2 grams.
l nitrogen eliminated during the period was, therefore, 66.7
or an average 16.7 grams per day. As in previous experiments,
pi. ine was collected during the second or work period in portions
Iding to eight-hour intervals. The table following shows
i of urine and the nitrogen in it:

:.-Amount of nitrogen eliminated in the urine (digestion experiment No. 225).

S8a.m. I 4p.m. 12 p. m.
: Period. to to to Total.
S4 p. m. 12 p. m. 8 a. m.


SC hof' rine ........... ..............grms. 333 300 352 985
* .:;Wt t oft nitrogen ...............................do.... 4.33 5.19 5.56 15.08
i toa nitrogen.................................... 1.30 1.73 1.58 ..........
o rin .................................grams.. 370 233 497 1,100
......... ....
.. f.o f nitrogen .................................do .... 5.18 4.12 6.51 15.81
re. s .. eto nitrogen...................................... 1.40 1.77 1.31 ..........
(: ::: of urine.................................grams.. 457 293 380 1,130
iitof: :;,;tWi of nitrogen .............................. 5.12 4.81 5.28 15.21
W: 'r t oet O anitrogn................................. 1.12 I 1.64 1.39 .......
: g of urine ............................... grams.. 355I 325 379 1,059
.Wreii t Of nitrogen ..............................do.... 4.197 5.85 5.95 16.77
t:::::. nitrogen.................................... 1.40 1.80 1.57 ..........
!:::: ":, .^ :.

-The table below shows the urine and its nitrogen content eliminated
i:the different, periods of the third (rest) period:

-. 32.-Amount of nitrogen eliminated in the urine (digestion experiment No. 226).

8 a.m. 4 p.m. 12 p. m.
Period. to tc to Total.
4 p.m. 12 p.m. 8 a. m.


gt of urine................................gram.. 300 350 618 1,268
of!Weig o nitrogen..............................do.... 4.80 6.06 7.29 18.15
elil:e:t of nitrogen .................................... 1.60 1.73 1.18 ..........
ct urine.......................... .grams.. 405 368 850 1,623
....e. g..h.tof nitrogen 5.02 5.59 6. 55 17.16
H-. Weht of mtrogen................................do.... 5.02 5.59 6.55 17.16
Eprent of nitrogen .................................... 1.24 1.52 .77 ..........
tf urine.. ..........................grams.. 427 615 797 1839
S tdi nitrogen.............................do.... 4.74 6.03 6.86 17. 62
s ..ofnitrogen.................................... 1.11 .98 .86 ..........
ig in ..............................grams.. 330 336 592 1258
toe..................... do.... 3.89 5.14 6. 39 15.42
r tof nitrogen ...................................... 1.18 1.863 108..........










..... .. ... ... .. .
( ) ): )(:mm~((] ((:()):(m)mmmm m~mm(mm m Il m i m.


.... ... ... .. .- -:::..:... ..
..... .....










.. ....

The daily balance of income and outgo of nitrogen mn
periods of the above experiment follows:


TABLE 33.-Daily income and outgo of nitrogen in erperiii et No..'


INItBe_, Slu.


Periods.


-First period, rest........ ............................
Second period, work ............................
Third period, rest ............. ....................


Time.


In food. IIn


feoee


nut


I I I I


Days.
4
4
4


Granms.
18.49
18.30
18.30


1.44
1.47
0"U" Ir


EXPERIMENT NO. 24. .


The experimental conditions in this were the same as in th
ceding experiment. The subject performed during the second VVi
period 1,349,157 foot-pounds, or 46,717 kilogrammeters of esUti
muscular work. This was equivalent to 109 calories, or 27 .aos
S ..... .. .. .
per day. As in previous cases, the work consisted in walking pi li
down hill. The number of trips made was 75. 'I

Subjec.-Chemist B, age 23 years. .
Weight (without clothing).-At the beginning of the experiment 56.1 -idg
(123.5 pounds); at the end of the first period and the beginning of the second' i
55.9 kilograms (123 pounds); at the end of the second and the beginning of
period, 55.6 kilograms (1224 pounds); at the end of the experiment, 55A.811_ogm0q
(122j pounds).
Duration.-The three experimental periods, each of four days' duration, beg
breakfast, respectively March 23, 26, and 30.


S: : ..... ..:;;-C

i::.i. I:



S :.... ...i."- ...o ..





S .:. ..." ::
..:I:..:. ;'.:..rhir h


** -. ::
"I
*1-
". "l:'.-!' ii ::


* M::

I''
...: : ..::';:' ;
.. ...:;, :
":':. 1'
A ; :".:::ii:i
.. .:.., I :


12
.. .. .....:: .
.. ... = :
...... .::.l


-- --


-- ---- --









33


TABLE 34.-Results of experiment No. 24.


Labo-
ratory
num-
ber.


449
628
65
480
056
4865



















449
628
W685
480
506
485
527
526




537


Food materials.



FIRST PERIOD
(REST).
Digestion ezperi-
meat No. 227.

EUgg.............
Butter............
Milk.............
Gelatin ..........
Oatmeal .........
Rice.............
Bread ............
Potato chips......
Sugar.............
Coffee ............

Total ........

Feces (water-free)
Urine .............

Amount digested.

Coefficients of di-
gestibility (per
cent) ...........
SECOND PERIOD
(WORK).
Digestion experi-
ment No. 2S8.

Eggs .............
Butter...........
Milk..............
Gelatin..........
Oatmeal..........
Rice.............
Bread ...........
Potato chips......
Sugar.............
Coffee ...........

Total .......

Feces (water-free)
Urine............


Weight
of ma-
terial.


Grams.
608
80
5,600
100
280
120


Total
Organic
matter.


Grams.
147
70
712
99
252
109


700 470
80 74
500 500
400 1

......... 2,434

101 78
4,944 ........

......... 2,356


96.8


608
80
5,600
100
280
120
700
80
500
400


......... 2,441

105: 82
3,894 .........


Amount digested. .... ....1 2,359


Coefficients of di-
gestibility (per
cent)...........
THIRD PERIOD
(REST).
Digestion experi-
ment No. 2S9.

Eggs ..............
Butter............
Milk.............
Gelatin ..........
Oatmeal .........
Rice.............
Bread ............
Potato chips......
Sugar.............
Coffee ............

Total ....

Feces (water-free)
Urine.............

Amount digested.

Coefficients of di-
gestibility (per
cent) ..........


96.7


608
80
5,600
100
280
120
700
80
500
400


106
4,225


147
70
740
99
252
109
470
74
500
1

2,462

84


Nitro-
gen.


Grams.
12.65
.24
30.80
.75
S6.86
1.60
11.13
1.00

.16

65.19

5.14
50.11


IProtein.







Grams.
79
2
193
5
43
10
70
6

1

409

32


60.05 377


92.1


92.2


Fat. Carbohy-
Fat rates.






Grams. Grams.
68 ..........
68 ..........
260 259
......... 94
94
20- 189
.........1 99
9 391
27 41
......... 500


452 1,573

19 27

433......... ... 1,546
433 1,546


95.8


98.3


- I- -I I- ~


12.65
.24
30.24
.75
6.86
1.60
11.13
1.00

.16


64.63


5.38
52.42


59.25


91.7


12.65
.24
30.24
.75
6.86
1.60
11.13
1.00
...... .
.16

64.63

5.51
56.75


68 ..........
68 ..........
260 270
......... 94
201 189
......... 99
9 391
27 41
.......... 500
......... ..........


Ash.


Grams.
6
2
43
5
1
7
4


68

23

45


1-I1


66.2


6
2
41
5
1
7
4


I I I


405 452 1,584

33 29 20

372I 423 1,564
372 4 23 I 1,564


91.9 i


79
2
189
5
43
10
70
6


405

34
..........


......... 2378 59.12 371


96.6


91.5


91.6


93.6


98. 7


68 .........
68 .........
281 270
......... 94
20 i 189
99
9 391
27 41
500


473 1,584

29 21


444 1,563


93.9 98.7


66

22

44


-x-


93.3


13,111

444
465

12,202


66.7 93.1
-!


6
2
44

5
1
7
4


69

22


13,308

436
464


47 12,408


68.1


93.2


1326-No. 117-02----3


111


I


n!=


Heat of
com buts-
tion
calcu-
lated.





Calories.










13,088

405
471

12,212


""""''








34


On the first day of the first (rest) period the urine excreted am
to 1,324 grams, with a nitrogen content of 0.79 per cent, or 10.5
on the second day the amount of urine was 1,073 grams, its nit
content 1.07 per cent, or 11.7 grams; on the third day the asn
excreted 1,130 grams urine, containing 1.20 per cent, or 13.6
nitrogen; and on the fourth day 1,397 grams urine, containing 1.
per cent, or 14.4 grams. The total nitrogen excreted in the per
was, therefore, 50.2 grams, the average amount per day 12.5 gram
In the second (work) period the urine was collected in portions cori
responding to eight-hour intervals. The details of the amounts
urine and nitrogen in it follow:

TABLE 35.-Amount of nitrogen eliminated in the urine (digestion experiment No. 2 ).

8a.m. 4 p. m. 12 p. m.
Period. to to to Total..
4p.m. 12p.m. 8a.m.

First day:
Weight of urine.................................grams.. 455 I 466 193 1,114
Weight of nitrogen................................do.... 4.32 4.66 2.90 11.88
Per cent of nitrogen .................................... .95 1.00 1.50........
Second day:
Weight of urine.................................grams.. 408 418 183 1,009
Weight of nitrogen.............. ................do.... 4.57 5.43 2.85 12.85
Per cent of nitrogen .................................... 1.12 1.30 1.55..........
Third day:
Weight of urine .......... ............... .......grams.. 341 290 220 851
Weight of nitrogen...............................do... 4.81 4.64 4.14 18.59
Per cent of nitrogen ..................................... 1.41 1.60 1.88 ..........
Fourth day:
Weight of urine..................................grams.. 345 339 236 920
Weight of nitrogen...............................do.... 4.69 4.95 4.46 14.10
Per cent of nitrogen..................................... 1.36 1.46 1.89.........


The amount of urine excreted in the different periods of the third
(rest) period, together with its nitrogen content, is shown in the follow-
ing table:

TABLE 36.-Amnount of nitrogen eliminated in the urine (digestion experiment No. S59}).

8 a. m. 4 p. in. 12 p. m.
Period. to to to Total.
4 p.m. 12 p.m. 8 p. m.

First day:
Weight of urine'............................... grams.. 373 433 214 1,0o!
Weight of nitrogen ...............................do.... 5.00 5.59 3.86 14.41
Per cent of nitrogen........................................ 1.34 1.29 1.80 .......
Second day:
Weight of urine ..............................grams.. 465 426 195 1,
Weight of nitrogen...............................do.... 5.35 5.50 3.74 14.
Per cent of nitrogen ..................................... 1.15 1.29 1.92....
Third day:
Weight of urine................................grams.. 384 410 218 1,
Weight of nitrogen................................do... 4.92 5.13 4.14 14
Per cent of nitrogen............. ..................... 1.28 1.25 1.90 .......
Fourth day:
Weight of urine................................grams.. 438 465 204
Weight of nitrogen...............................do.... 4.95 5r07 3.51
Per cent of nitrogen.............. .................... 1.13 1.09 1.72 .








35


Following the same methods as before, the daily income and outgo
of nitrogen was calculated. The nitrogen balance follows:

iTABLE 37.-Daily income and outgo of nitrogen in experiment No. 24.

Nitrogen.
Periods. Time.
In food. In feces. In urine. Gain.

Days. Grams. Grams. Grams. Grams.
Fest period (rest)............... ................... 4 16.30 1.29 12.53 2.48
Second period (work) ............................... 4 16.16 1.35 13.11 1.70
Third period (rest)................................. 4 16.16 1.38 14.19 .59


EXPERIMENT NO. 25.

This experiment was made under the same experimental conditions
as the two immediately preceding. The muscular work performed
during the second period consisted in making the trip up and down
hill 75 times, which yielded according to the method of calculation
followed, 1,409,119 foot-pounds, or 48,849 kilogrammeters. This was
calculated to be equal to a total of 114 calories, or 18 calories per day.
Subject.-Student C, age 22 years.
Weight (without clothing).-At the beginning of the experiment 64.1 kilograms (141
pounds). The weight did not change during the first and second period. At the
end of the third period it was 64.6 kilograms (142 pounds).
Duration.-The three experimental periods, each of four days' duration, began with
breakfast March 22, 26, and 30, respectively.


. ... ... .. ...










36


TABLE 38.--Resus of experiment No. 25.


Food materials.


FIRST PERIOD
(REST).
Digestion experi-
ment No. 230.


Eggs..............
Butter...........
M ilk..............
Gelatin...........
Oatmeal .........
Rice......... ...
Bread............
Potato chips.....
Sugar.............
Coffee............


Weight Total
of ma- organic
trial. matter.






Grams. Grams.
584 141
80O 70
5,600 1 712
100 99
280 252


120
900
160
500
400


Total ....... ........


Feces (water-free) 90
Urine............ 4,514

Amount digested .........

Coefficients of di-
gestibility (per
cent) ........ .......


449
528
525
480
505
485
527
526




533












449
528
535
480
505
485
527
526


584
80
5,600
100
280
120
900
160
500
400


Total ................

538 Feces (water-free) 100
Urine............. 3,264

Amount digested. ........

Coefficients of di- I
gestibility (per
cent) ........... .........

THIRD PERIOD


(REST).
Digestion experi-
ment No. 32.
Eggs.............
Butter ............
Milk.............
Gelatin ...........
Oatmeal ..........
Rice ............
Bread............
Potato chips......
Sugar.............
Coffee.............

Total ....... :

Feces (water-free)
Urine ............

Amount digested. .

Coefficients of di-
gestibility (per
cent) ........... .


584
80
5,600
100
280
120
900
160
500
400

.........


110
3,782


109
604
147
500.
12

2,635


68
=.........I


Nitro-
gen.


Grams.
12.15
.24
30.80
.75
6.86
1.60
14.31
2.00

.16


68.87


4.37
61.24


2,567 I 64.50
.-L


Protein.


Grams.
76
2
193
5
43
10
90
12

1


Fat.


Carbohy-
drates.


Grams. Grams.
65 ..........
68 .........
260 259
......... 94
20 189
......... 99
11 503
53 82
......... 500
......... ..........


I----1----- I I-


SI I li


27
...... ...


15
.....


I -1 1


1,726


26
... ... ..


1,700


:1.i I


97.4 93.7


I


141 12.15
70 .24
719 I 30.24
991 .75
252 6.86
109 1.60
604 14.31
147 2.00
500 .........
1 .16


2,642


77
--...--.--
2,565


97.1


68.31


93.8


76
2
189
5
43
10
90
12

1


96.9


65
68
260

...... ..
11
53


98.5


270
94
189
99
503
82
500
..........


Ash.


Greaes. Cbrfli1
6 .....,, l
2 ......-,
e .--...--.

I



----I--------
8 .-....-..
:::::::::i.........


22


~s-


53 13,2S


70.7


6
2
41

6
1
10
8


~ .9


.1 4 .1 N i


1,737


........ .

.14,12.
-- ------ --


5.02 31 28 18 22 417
59.40 ........................ ......... 46

63.29 397 449 1, 719 51 13 19i


92.7


141 12.15
70 .24
740 30.24
99 .75
252 6.86
109 1.60
604 14.31
147 2.00
500 .........
1 | .16

2,663 68.31


92.8


94.1


99.0


I i i -


76 65
2 68
189 281
5 .........
43 20
10 .........
90 11
12 53

S .........


I~ i :r


87 5.36 34
......... 54.58 .........

2, 576 62 95 394


96.7 92.2 92.1


461


92.6


..........
270
94
189
99
503
82
500


1,737


69.9


6
2
44

5
1
10
8


76


16 23


1,721 53


99. 69.7
99.1 69.


9.5


.......ma
.-.a..-.

..--a-..

..zZJ.w


Labora-
tory
num-
ber.


SECOND PERIOD
(WORK).
Digestion experi-
ment No. 231.
Eggs..............
Butter............
Milk .............
Gelatin............
Oatmeal ..........
Rice ..............
Bread ............
Potato chips......
Sugar.............
Coffee.............


449
5i28
540
480
505
485
527
526




543


:









37


On the first day of the first (rest) period the subject excreted 842
grams of urine, containing 1.92 per cent, or 16.2 grams nitrogen; on
the second day 910 grams urine, containing 1.69 per cent, or 15.4
grams nitrogen; on the third day the total urine excreted equaled
1l065 grams, its nitrogen content 1.37 per cent, or 14.6 grams; on
'the fourth day of the period the urine excreted equaled 1,697 grams
with a nitrogen content of 0.89 per cent, or 15.1 grams. The total
amount of nitrogen excreted in the urine during the period was, there-
fore, 61.2 grams, or 15.3 grams per day.
As was the case during the preceding experiments, the urine was
collected in the second (work) period in portions corresponding to
eight-hour intervals, and its nitrogen content determined. The results
follow.

TABLE 39.-Amount of nitrogen eliminated in the urine (digestion experiment No. 231).


Period.


8a.m. 4p.m.
to to
4 p. m. 12 p. m.


First day:
Weight of urine....................................grams..
Weight of nitrogen......... .............. do....
Per cent of nitrogen .................................
Second day:
Weight of urine................................grams..
Weight of nitrogen................................do....
Pei cent of nitrogen..................................
Third day:
Weight of urine.................................grams..
Weight of nitrogen.................................do.....
Per cent of nitrogen........................ ..............
.Fourth day:
Weight of urine.................................. grams..'
Weight of nitrogen.....................do............do...
Per cent of nitrogen.......................................


344
4.44
1.29


299
5.17
1.73
270
5.02
1.86
277
5.18
1.87


335
5.39
1.61
387
7.20
1.86
308
5.85
1.90
319
6.06
1.90


12 p. m.
to Total.
8a. m.


190
3.84
2.02


165
3.48
2.11
155
3.58
2.31
215
4.19
1.95


869
13.67

851
15.85

' 733
S 14.45

811
15.43
..........


The details of the amount of urine and nitrogen in it excreted during
the eight-hour periods of the third (rest) period of this experiment are
as follows:

TABLE 40.-Amount of nitrogen eliminated in the urine (digestion experiment No. 232).


Period.


First diy:
Weight of urine ................................. grams..
Weight of nitrogen.................................do....
Per cent of nitrogen ......... .................... .....
Second day:
Weight of urine.................................. grams..
Weight of nitrogen............................... do....
Per cent of nitrogen .....................................
Third day:
Weight of urine.................................. grams..
Weight of nitrogen...............................do....
Per cent of nitrogen ......... .................... .....
Fourth day:
Weightof urine ......................... ....... grams..
Weight of nitrogen...............................do....
Per cent of nitrogen ....................................


8a. m. 4 p.m.
to to
4 p. m. 12 p. m.


322
5.22
1.62
562
6.18
1.10
180
2.75
1.53
242
4.02
1.66


480
6.38
1.33
322
4.93
1.53
365
5.62
1.54
304
5.02
1.65


12 p. m.
to Total.
8a. m.


380
3.50
.92


2
3.6
1.5
17
3.4
1.9
2
3.1
1.1


1,182
15.10
-.--------


35 1,119
67 14.78
56 ..........
75 720
40 11.77
94 .........
15 761
89 12.93
81 ..........




w


38


The table below shows the daily balance of income and outgo
nitrogen during the whole experiment:

TABLE 41.-Daily income and outgo of nitrogen in experiment No. 65.


| Nitrogen.


Periods.


First period, rest.....................................
Second period, work................................
Third period, rest ..................................


SUMMARY OF COEFFICIENTS OF DIGESTIBILITY.


In the preceding pages data are given which show the amount of
protein, fat, and carbohydrates digested, as well as the energy of the
total digested food. Such data are summarized in Table 42, the results
being compared with those obtained in the similar investigation pre-
viously reported


TABLE 42.-Summary of coefficients ofdigestibility of a simple mixed
available.


diet, and the energy


Sub-
ject.


Character of experiment.


Protein.


Per cent,
A Rest................................... 91.6
A Work .................................. 91.2
A Rest....-................................ 92.2
B .....do ................................ 92.0
B W ork ................................... 91.5
B Rest................................. .... 91.5
C .....do .................................. 92.4
C Work ................................... 92.6
C Rest......-.............................. 92.9
A .....do .................................. 92.2
A W ork ................................... 91.6
A Rest.................................. 91.4
B .....do ................................. 91.7
B Work ...................................... 92.0
B Rest..................................... 91.7
C .....do .................................. 92.6
C Work ................................... 92.5
C Rest..................................... 92.7
A .....do .................................. 92.2
A Work ................................... 92.2
A Rest..................................... 91.9
B .....do ................................. 92.2
B Work ................................... 91.9
B Rest..................................... 91.6
C .....do .................................. 93.8
C Work .................................. 92.8
C Rest..................................... 92.1
Average, rest experiments:
A, 6 experiments............................ 91.9
B, 6 experiments............................ 91.8
C, 6 experiments............................ 92.7
Average, 18 experiments ............. 92.2
Average, work experiments:
A, 3 experiments............................ 91.7
B, 3 experiments........................... 91.8
C, 3 experiments........................... 92.6
Average, 9 experiments .............. 92.0


Average, all (27) experiments.........
I


92.T1


Fat.


Carbohy-
drates.


Energy.


SI _1


Per cent.
95.9
96.4
96.7
94.0
94.0
94.1
94.3
92.7
94.8
94.2
95.5
95.2
92.4
93.8
93.0
92.4
93.2
94.4
95.9
95.3
95.1
95.8
93.6
93.9
96.9
94.1
92.6
95.5
93.9
94.2


Per cent.
97.7
97.8
97.9
98.3
98.4
98.4
98.3
98.6
98.4
98.4
98.4
98.1
98.8
99.1
98.7
98.8
99.0
98.5
98.2
S98.3
98.4
98.3
98.7
98.7
98.5
99.0
99.1
98.1
98.5
98.6


Per cent.
92.6
92.7
O.o
93.0
929
93.0
98.1
9.0
96.4
92.5
St9
92.s
92.5
92.7
92.8

93.1
98.6
92.8
9as
93.1
93.8
98.1
98.2
93.5
98.4::::

92"8
ao,
ad '::i


94.5 98.4 .3(

95.7 98.2 9.
93.8 98.7 S..
93.3 9.9 9M9


94.3


94.5


98.6


98.5


a U. S. Dept. Agr., Office of Experiment Stations Bul. 89.


Time.


Days.
4
4
4


In food.

Grams.
17.22
17.08
17.06


In feces.

Grams.
1.09
1.26
1.34


In urine.

Grams.
15.81
14.85
13.66


Gatin

a-mn
0.82
LOB
2.09


Num-
ber of
experi-
ment.


206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232


I-~------t




I IN


39

From the table it appears that there was practically no difference
in the average thoroughness of digestion of the ration when the sub-
jects rested and when they performed rather severe muscular work.
Slight variations are noticeable in the coefficients of digestibility
obtained with the different subjects, but these are not sufficient for gen-
eral deductions. Individuality appeared to have much less effect upon
the digestion than might be expected. The average results agree
quite closely with those previously obtained when it is remembered
that the diet in the two series of experiments though similar was not
the same. Considering the experiments as a whole, the differences in
coefficients of digestibility between the periods of work and rest are
less marked than those observed when the conditions as regards work
performed were uniform. This is strong evidence that the average
results of a considerable number of digestion experiments may be
assumed to actually represent the digestibility of the different nutrients
in a given diet, and that such averages may be used in calculation.

METABOLISM OF NITROGEN.

The income and outgo of nitrogen was determined in the experiments
reported in this bulletin, the special object being to secure information
regarding the nutrients, which are the actual source of muscular work.
It was assumed that if protein was required for performing external
muscular work more nitrogen would be excreted in the urine under
the experimental conditions in the period in which muscular work was
performed than in the periods in which the subject remained as inac-
tive as possible. There are those who maintain that muscular work is
performed at the expense of nitrogen- free nutrients, and that under
ordinary circumstances protein is not the source of energy, but is
required for the formation and repair of body tissue. Other physiolo-
gists hold that while nitrogen-free nutrients are usually the source of
muscular energy, yet, if the work is protracted enough, or severe
enough to induce labored breathing, the energy must be supplied by
protein. Judging by the results of the investigations conducted under
the auspices of this Department, it appears that, provided the carbohy-
drates and fat in the diet are abundant and the protein is not excessive,
the nitrogen-free nutrients are the usual source of energy for external
muscular work.
In the early experiments made at the University of Tennessee the
diet was quite abundant, and under the different experimental condi-
tions little change in the amount of nitrogen excreted in the urine
was observed, which could be attributed to an increased metabolism of
protein in the work periods. In the present experiments the diet was
more limited in amount, though in the majority of cases it was normal
in the proportion of nitrogen-free to nitrogenous nutrients.


c.Ii


....r;..~~i.~. ......;








Ir


The balance of income and outgo of nitrogen, as well as the avai

energy in a food, and the average heat equivalent of the work

formed in the different work experiments, is shown in the flowi

table:

TABLE 43.-Daily income and outgo of nitrogen and energy in metabolism e peria
Nos. 17-25, with work actually measured.


Character
of
experi-
ment.


t
0.


3H"
W0)
gC
sW
jE





17

18


Kgs.
-0.45

+ .34
+ .34
+ .23
- .23




; .4
+ .45
.23




-1.13

- .68
+ .45



- .34
- .34
+ .23

+ .68
+ .45


Nitrogen.


Va


s.a
MQ.





206



207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232


Gms.
1.75
1.74
1.60
1.51
1.51
1.57
1.44
1.37
1.35
1.52
1.59
1.62
1.44
1.35
1.41
1.33
1.31
1.29 I
1.44
1.46
1.47
1.29
1.35
S1.38
1.09
1.25
1.34


-I


Gms.
17.56
17.92
17.61
13.01
14.28
14.18
14.29
16.44
16.77
17.98
16.75
17.45
12.22
13.73
13.66
14.24
15.61
15.52
16.69
15.72
17.09
12.53
13.11
14.19
15.31
14.85
13.65


+I
Uo

C
1-
0




+1.57
+ .42
+1.27
+4.02
+2.15
+2.49
-+3.20
+ .52
+ .51
- .07
+ .73
- .03
+3.59
+1.91
+1.88
+2.28
+ .67
+ .74
+ .36
+1.12
- .26
+2.48
+1.70
+ .59
+ .82
+ .97
+2.09


Energy.


Calo-
ries.
3,960
3,912
3,898
3,687
3,651
3,640
3,848
3,812
3,802
3,442
4,016
3,483
3,175
3,748
3,206
3,361
3,932
3,392
3,479
3,488
3,555
3,272
3,278
3,327
3,522
3,528
3,577


Clo-
0
o-4



ries.
143
142
124
126
133
126
128
134
116
119
133
123
114
118
113
114
125
108
110
118
114
101
111
109
88
104
113


a




Calo-
ries.
149
143
148
133
128
130
137
132
136
140
136
136
124
122
121
129
127
127
133
132
132
118
116
116
126
124
123


Work
messruS.


COlo-
ries. Kgms.
3,668 .........
3,627 55,876
3,626 ........
3,428 ........
3,390 48,849
3,384 ........
3,583 .......
3,546 50,992
3,550 .......
3,183 .......
3,747 39,421
3,224.......
2,937 ........
3,508 42,422
2,972 ........
3,118 ........
3,680 45,421
3,157 ........
3,236 .......
3,238 41,565r
3,309 ........
3,063 .........
3,051 46,717
3,102 ........
3,308 ........
3,300 48,849
3,341 ........


io I-

:...
"iib'
180.4



114.0




9. 0 :i
99.0 :

'io&6 |
I--- :

...-. i.
97.0

IOL9.0


No constant difference was observed in the amount of nitrogen

excreted in the urine in different periods which could be attributed to:

the muscular work performed.


COMPOSITE SAMPLES.


A considerable part of the labor involved in conducting experiment

like those reported in this bulletin is due to the fact that each fo

material is analyzed. It was believed that if a composite sample

made up of aliquot portions of the different foods in any given rati.

the analysis of such sample would show the average composition'

the ration as a whole. To determine the accuracy of this meth

composite samples were made of the diet supplied in sixteen of

experiments reported in this and a former bulletin," and the rele


a U. S. Dept. Agr., Office of Experiment Stations Bul. 89.


Rest ......
Work .....
Rest ......
Rest ......
Work .....
Rest ......
Rest .....
Work .....
Rest ......
Rest ......
Work .....
Rest ......
Rest ......
Work .....
Rest ......
Rest ......
Work .....
Rest ......
Rest ......
Work .....
Rest ......
Rest ......
Work.....
Rest ......
Rest ......
Work .....
Rest ......


0

i-4


Gms.
20.88
20.08
20.48
18.54
17.94
18.24
18.93
18.33
18.63
19.43
19.07
19.04
17.25
16.99
16.95
17.85
17.59
17.55
18.49
18.30
18.30
16.30
16. 16
16. 16
17.22
17.08
17.08


40









compared with the average values for the ration computed from the
analyses of the different foods composing it. Sugar was not included
in the composite sample, and the data derived from the analysis of
sugar are also omitted in computing the average composition of the
ration from the analyses of individual foods. It was believed that this
omission would not affect the value of the results, as sugar, of course,
contains no nitrogen; furthermore, it was convenient to omit the sugar
as at best the composite sample was bulky and therefore rather difficult
to handle satisfactorily. Z1
In experiments Nos. 53, 56, and 59 the ration consisted of Hamburg
steak, butter, milk, oatmeal, bread, and potato chips. In experiments
Nos. 62 and 65 the ration was made up of the same materials, except
that Hamburg steak was omitted and cracked corn was added. The
ration in experiments Nos. 99, 102, and 105 was made up of milk, oat-
meal, potato chips, bread, canned beef, and butter. In experiment
No. 108 the ration was the same in character, except that gelatin was
added. Sugar was used in all the rations, but, as previously noted,
was not included in the comparison. In some of the experiments coffee
was taken as a beverage, but the amount of nutrients thus added to
the ration is-so small that it is believed that this material may be left
out of account without introducing any appreciable error.
In nine of the tests (digestion experiments Nos. 53, 56, 59, 62, 65,
99, 102, 105, and 108)a one-fifth of the total amount of the several food
materials was taken as an aliquot portion. In seven later tests (diges-
tion experiments Nos. 147, 150, 153, 156, 159, 165, and 168) the pro-
portion was diminished to one-tenth. In these tests the analyses of
the composite samples were made in duplicate to study still further
the accuracy of the method. It seemed probable that if the composite
sample did not represent very closely the average composition of the
ration, or, in other words, if it was not a uniform mixture, the dupli-
cate analyses would not agree at all closely.
The materials making up the composite sample were thoroughly
mixed and then dried, ground, subsampled, and analyzed in the usual
way.
The calculated composition of the ration was learned by dividing
the sum of the amounts of any given nutrient in the several foods by
the total nutrients in the ration. Thus in experiment No. 53 the total
weight of organic and mineral matters in the food, leaving out the
sugar as already explained, was 1,252 grams. The total protein in
the different articles making up the diet was 267 grams. Therefore the
ration as a whole contained 21.33 per cent protein (267+1,252=21.33
per cent).
In Table 44 a comparison is made of the results obtained by analyz-

aTU. S. Dept. Agr., Office of Experiment Stations Bul. 89.
1326-No. 117- 02- 4


I~








42


ing the composite samples of the several rations and by ca
their composition from the analysis of the several food material

TABLE 44.-Quantities and proportions of nutrients in ration computed from
of individual food materials and from that of the composite sample.

Quantities of nutrients in ration for Percentage competition of
four days. free material.
Character of analyses.
rotein at. Car boh- Ah.Protein. Fat. Carbo -
drates. data OL1

Experiment No. 53: Grams. Grams. Grams. Grams. Per ent. Prer et. J ir cen. lird
By individual analyses. 267 390 547 48 21.33 31.15 4.a 6 8
By composite analysis... 268 385 551 47 21.43 30.78 44.08 i3
Experiment No. 56:
By individual analyses. 278 296 545 44 23.91 25.45 46.86 Lh
By composite analysis... 282 296 539 46 24.21 25.48 46.37 &U
Experiment No. 59: ....
By individual analyses 295 311 521 48 25.11 26.47 44.31 4."
By composite analysis... 300 322 505 48 25.53 27.38 43.00 4t
Experiment No. 62:
By individual analyses. 218 271 456 38 22.18 27.56 46.39 .L
By composiLeanalysis..., 218 266 460 39 22.22 27.03 46.77 3.9
Experiment No. 65:
By individual analyses 239 271 579 39 21.19 24.03 51. 33 .4
By composite analysis... 239 276 572 40 21.20 24.48 50.73 1 L
Experiment No. 99:
By individual analyses 248 279 570 42 21.77 24.50 50.04 L..
By compositeanalysis... 263 271 566 38 23.13 23.82 49.7 &86
Experiment No. 102: --
By individual analyses. 185 212 562 32 18.67 21.39 56.71 L2.
By composite analysis... 192 199 568 32 19.39 20.07 67.36 .lM1
Experiment No. 105:
By individual analyses. 210 243 563 35 19.98 23.12 68.67 L
By composite analysis... 226 239 550 36 21.47 22.79 52.34 4IPi
Experiment No. 108:
By individual analyses. 262 307 646 44 20.81 24.39 51.31 ..a
By composite analysis... 266 293 656 44 21.11 23.31 52.11 3.4
Experiment No. 206:
By individual analyses. 522 559 1840 84 17.37 18.60 61.24 293
By compositeanalysis... 544 585 1781 95 18.10 19.46 59.27 S.V
Experiment No. 209:
By individual analyses. 464 517 1751 73 16.54 18.43 62.43 2.
By composite analysis... 486 532 1699 88 17.31 18.97 60.50 &l I
Experiment No. 212:
By individual analyses 473 521 1885 74 16.02 17.64 63.84 3.S
By composite analysis... 478 532 1856 87 16.20 18.01 62.85 2.91
Experiment No. 215:
By individual analyses. 486 503 1517 86 18.75 19.40 68.58 L.
By compositeanalysis... 494 493 1515 90 19.04 19.00 68.50 3.
Experiment No. 218:
By individual analyses. 432 461 1428 73 18.04 19.26 59.65 .&.S
By compositeanalysis... 428 448 1443 75 17.87 18.73 60.26 .14
Experiment No.224:
By individual analyses. 463 506 1577 83 17.61 19.25 59.99 g .1
Bycompositeanalysis... 473 470 1600 86 18.00 17.86 60.88 S .
Experiment No. 227:
By individual analyses. 409 452 1573 68 16.35 18.071 62.86 2.92
By composite analysis... 406 463 1565 68 16.21 18.50 62.56 2.6


It will be seen that the agreement between the composition of tmi
ration as shown by the analysis of composite samples and as computed
on the basis of analyses of individual foods is quite close. When tin
results of duplicate analyses of the same composite sample were
pared the same close agreement is found. In accordance with h
usual practice, these data are not reported. In all cases the discre
cies are not greater than are to be expected from the analysis
different samples of such foods as meat, fish, etc., or in some
even in duplicate analyses of the same sample. Furthermore, it j
be remembered that the calculated composition of the ration in
the result of all the errors in the analysis of the different foods.
proportion of error in the analysis of composite samples it wo




E t ~


43


appear must be lower, as the total number of determinations is not
nearly as large.

It is interesting to compare the coefficients of digestibility obtained
in the different work and rest periods in the earlier experiments at
the University of Tennessee and those reported herewith when the
composition of the ration is obtained by the two methods.

TABLz 45.-Cefficients of digestibility of nutrients computed from composition of individual
food materic Is and from that of composite samples.


Character of analyses.


Experiment No. 68:
By individual analyses ........................
By compiteanalysis.........................
zxpmten~ ~ No. 56:
tuadividual analyses........................
cr. composite analysis.......................
tmet No. 59:
By individual analyses ......................
By composite analysis.........................
Zxperliment No. 62:
By individual analyses........................
By composite analysis.........................
Experiment No. 65:
By individual analyses ...................
By composite analysis .......................
Experiment No. 99:
By Individual analyses.......................
By. composite analysis.......................
pelmenltJNo. 102:
Byindividual analyses........................
By composite analysis..........................
Experiment No. 105:
By individual analyses.......................
By composite analysis .......................
Experiment No. 108:
By individual analyses........................
By composite analysis..........................
Experiment No. 206:
By individual analyses ......................
By composite analysis..........................
Experiment No. 209:
By individual analyses .......................
By composite analysis........................
Experiment No. 212:
By individual analyses .......................
By composite analysis.........................
Experiment No. 215:
By individual analyses .......................
By composite analysis.........................
Experiment No. 218:
By individual analyses .......................
By composite analysis.........................
Experiment No. 224:
By individual analyses ......................
By composite analysis.........................
Experiment No. 227:
By individual analyses ........................
By composite analysis..........................


Protein.


Fat.


Per cent. Per cent.
94.4 96.9
94.4 96.9
94.2 94.9
94.3 94.9
94.2 94.9
94.3 95.0
91.7 97.0
91.8 97.0
93.3 96.7
93.3 96.8
92.7 95.7
93.2 95.6
91.4 88.2
91.7 87.4
92.9 95.5
93.4 95.4
92.8 94.5
92.9 94.2
91.6 95.9
91.9 96.1
92.0 94.0
92.4 94.2
92.4 94.3
92.5 94.4
92.2 94.2
92.3 94.1
91.7 92.4
91.6 92.2
92.2 95.9
92.4 95.5
92.2 95.8
92.1 95.9


The agreement between the results
again seen to be very close.


obtained by the two


From the results of the above comparisons it seems fair I
that the composition of a given diet may be learned with
S. ecuracy by the analysis of a composite sample made up


methods is


to conclude
reasonable
of aliquot


portions of the different foods in the ration, and that this method may
e advantageously followed in digestion experiments and similar

Investigations where the amount of analytical work is at best neces-

ly large.
~ 1~C-'


Energy.


Per cent.
90.8
i..........
90.8
..........
88.9
....91.2..

91.2
..........
91.2
..........
90.0

88.8
......- ..
89.4
----------
90.1


..........
..........
..........

-----....--......

..........
...........
..........
..........


..........
..........
..........
.... ....


Carbohy-
drates.


Per cent.
96.1
96.2
98.0
98.0
96.5
96.5
95.9
95.9
97.6
97.6
96.8
96.8
98.2
98.2
96.1
96.0
97.5
97.6
97.7
97.6
98.3
98.3
98.3
98.2
98.4
98.4
98.8
98.8
98.2
98.3
98.3
98.3


Ash.


Per cent.
66.7
66.0
65.9
67.4
66.7
66.7
55.3
55.4
61.5
62.5

52.4
47.4
56.3
56.3
62.9
63.9
56.8
56.8
56.0
61.0
67.1
72.7
67.6
72.4
58.1
60.0
64.4
65.3
61.5
62.8
66.2
66.2


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