Jan. io; 1916 
Mature Beef and Immature Veal 
69s 
In experiments 15 to 24, because of the comparatively large weight of trypsin used, 
it was desirable to ascertain how much of the trypsin nitrogen appeared in the neu¬ 
tralized digestion filtrate and in the precipitate of alkali proteinate, in order that 
both may be corrected by the amounts found. Accordingly, two portions of trypsin 
1, each weighing 100 mgm., were dissolved in 100 c. c. of 0.5 per cent sodium carbo¬ 
nate and precipitated with 48 c. c. of Nj$ sulphuric acid, as in the digestion experi¬ 
ments. The mixtures were heated to a boil and filtered. The total nitrogen (iV/5) 
in the filtrates was 4.25 and 4.40 c. c.; in the precipitates, 0.47 and 0.70 c. 6. The 
•averages of these are recorded in Table X, and both were used as corrections, as 
already described on page 691. For trypsins 2 and 3 the term “trypsin nitrogen” 
in Table XI means the total nitrogen in the trypsin present in the 100 c. c. of diges¬ 
tion fluid. Trypsin 2 contained approximately 90 per cent of its nitrogen as ammo¬ 
nia, and consequently the amount precipitated with the alkali proteinate was dis¬ 
regarded. The results for alkali proteinate in experiments 31 to 34 with trypsin 3 
showed that the correction for alkali proteinate derived from the trypsin must have 
been similar to that in trypsin 1, and the determination of this correction was 
omitted. 
In experiment 18, for example; 100 c. c. of veal sample 5 digestion fluid were neutral¬ 
ized exactly four hours after the digestion began, and the mixture was brought to a boil 
and filtered. The filtrate contained 37.7 c. c. of iV/5 nitrogen, of which 4.3 c. c. 
were derived from the trypsin present and 7.8 c. c. from the extractives present before 
the digestion was begun; and the figure recorded, 25.6 c. c., is the amount of pro¬ 
teose, peptone, and amino-acid nitrogen actually formed by the digestive process. 
The precipitated alkali proteinate contained 6.3 c. c. of Nj$ nitrogen, of which 0.6 
c. c. was derived from the trypsin. The corrected figure, 5.7 c. c., is recorded in 
Table X. 
The results with trypsin are practically the same as those with pepsin. They 
indicate that both the beef and the veal digested with practically the same speed. 
The presence of only small amounts of alkali proteinate through the experiments 
indicates that just as soon as the beef or the veal goes into solution as alkali proteinate 
this is promptly split into the simpler molecules of proteoses, etc.—i. e., the equal¬ 
ity in speed of digestion pertains both to the first and to the later stages in the diges¬ 
tive process for both beef and veal. At no time was there any indication that either 
the beef or the veal contained any nitrogenous substances resistant to the action of 
the trypsin. In experiments 16 to 24, Table X, approximately 90 per cent of the 
veal had gone into solution at the end of 24 hours, with similar results for the beef. 
In experiments 26 to 34, Table XI, the rate of digestion was measured by both 
the second and third methods. The comparisons between veal sample 9 and skim- 
milk sample 2 in experiments 27 and 28 were made for the purpose of ascertaining 
whether the method used would detect a difference in rate of digestion when such 
a difference was large. Experiment 28 was a repetition of experiment 27. On 
account of the comparatively vigorous action of pepsin-hydrochloric-acid solution 
veal sample 5 in experiment 19 very soon “caught up” with skim-milk sample 1; 
but in experiments 27 and 28 the striking difference between the rate of digestion 
of skim-milk sample 2 and veal sample 9 was brought out by the less vigorous cleav¬ 
age of the trypsin-sodium-carbonate solution. The treatment of skim-milk sample 
2 was similar to that of skim-milk sample 1. Skim-milk sample 2 was obtained by 
skimming, with the aid of a siphon, a sample of ordinary pasteurized milk obtained 
from a dealer. One gm. of skim-milk sample 2 contained 1.88 c. c. of iV/5 total nitro¬ 
gen, or 0.529 per cent. The extractive nitrogen in experiments 27 and 28 was 11.6 
and 14.2 per cent, respectively, of the total. The specific gravity was 1.0334 at 
26° C. Six hundred gm. of skim-milk sample 2 were weighed into a 2-liter Erlen- 
meyer flask. The calculated volume of the skim milk was 580.4 c. c. To this 316.4 
