Jan. io, 1916 
Mature Beef and Immature Veal 
703 
Free ammonia formed during digestion. —Because of the slowness 
with which ammonia reacts with nitrous acid (see p. 681) it was desira¬ 
ble to determine the amount of ammonia formed during the digestion of 
mature beef and immature veal and incidentally to ascertain whether 
the amounts formed were significantly different for the two meats. In 
experiments 15, 18, 20, 22, and 24, after 24 hours' digestion, 100 c. c. 
portions of digestion fluid, containing 0.5 gm. of sodium carbonate and 
corresponding to 5 gm. of meat, were transferred to Kjeldahl flasks, 
diluted to 500 c. c. with distilled water, and the ammonia distilled into 
standard acid. The mixtures were quickly brought to a boil and boiled 
for half an hour. This method is known to give high results, but for 
the purpose of comparison the errors were negligible. In all cases except 
veal sample 7 the ammonia obtained neutralized 2 to 3 c. c. of iV/5 
acid, amounts too small to be a disturbing factor in using the third 
method or indicating any differences between the beef and veal. From 
veal sample 7, 7 c. c. of iV/5 ammonia was obtained. This animal was 
sick when purchased (see p. 675). On this score the comparatively 
high ammonia content of trypsin 2 was a disadvantage. 
Blanks on reagents. —It was found convenient to begin each diges¬ 
tion experiment with fresh alkaline permanganate solution in the 
absorption pipette and to make blank determinations on the nitrous- 
acid reagents, water, octyl alcohol, etc., before, during, and after a 
digestion experiment involving about 20 amino-nitrogen determinations. 
The blank on the reagents, allowing 20 minutes' reaction time, was 0.6 
c. c. nitrogen gas when the permanganate was fresh and rose to 1.2 c. c. 
after this reagent had been used until absorption had become slow (see 
p. 680). The smallest volume of nitrogen gas measured in the begin¬ 
ning of a digestion experiment was 3.3 c. c.; the largest, at the end of 
an experiment, 28.7 c. c. 
feeding experiments on cats 
In these experiments cats of various ages were fed on a diet in which 
immature veal was the sole source of nitrogen. 
Osborne and Mendel and their coworkers (1914, p. 334) in their investi¬ 
gations emphasize the difference between maintenance and growth. Ac¬ 
cording to these investigators an animal can not maintain its weight unless 
the diet contains tryptophan, although the diet may be physiologically 
sufficient in all other respects. Further, an animal can not grow unless 
lysin is present in the diet, the amount of growth being conditioned 
by the amount of lysin available. Conversely, the absence of these 
unique amino acids results in a decline in weight or in stunted 
growth. According to McCollum and his coworkers (Hart, McCollum, 
et al., 1911), a diet properly balanced for growth may not be properly 
balanced for reproduction—i. e., cows fed on either the whole corn plant 
or the whole wheat plant would grow, but vigorous calves would be 
produced only by the corn-fed cows. 
