Jan. io, 1916 
Mature Beef and Immature Veal 
701 
tions in which the pepsin-hydrochloric-acid solution was used bacterial 
action was excluded from the digestion mixtures by the bactericidal action 
of the 0.2 per cent hydrochloric acid. During the digestions in which 
trypsin-sodium-carbonate solution was used bacterial action was not 
excluded, because any bacteria introduced into the digestion mixtures 
would not be destroyed by 0.5 per cent sodium carbonate. When the 
digestion period was short (Tables X and XI)—i. e., 24 hours or less—the 
possible error due to such recently introduced bacteria was negligible 
because the proteolytic action of the most vigorous proteolytic bacteria 
is very weak when compared with that of trypsin. When the digestion 
period was long enough (Table XII) the chemical changes brought about 
by the bacteria may have appreciably affected the results. No preserva¬ 
tives were used in any of the digestion experiments. This was regarded 
as an almost necessary condition in view of the fact that both the whole¬ 
someness of immature veal and the influence of certain preservatives 
on digestion, health, etc., have been subjects of controversy. In the 
third method it was decided to carry on the digestions as aseptically 
as possible and to regard the results obtained in the first 48 hours as 
practically uninfluenced by bacteria. Generally after a few days putre¬ 
factive odors were noticed in the digestion mixtures. In so far as a 
very strong putrefactive odor can be caused by slight chemical changes 
in which small amounts of strongly odoriferous substances are pro¬ 
duced, the amino determinations were made as late as 12 days after 
beginning the digestion in mixtures that were undoubtedly putrefying 
as judged by the odor. The practical necessity of a long digestion 
period in the third method, because of the slowness of amino-nitrogen 
liberation, together with the indeterminate effect of bacteria, is an objec¬ 
tion to this method. The results of the first and second methods showed 
that under similar conditions mature beef and immature veal proteins 
were digested to the proteose and peptone stage with practically equal 
speed. However valuable such data may be they are not complete 
until the speed of the last transformation in the digestive process is 
measured for both. If the rate of liberation of amino groups in imma¬ 
ture veal had been found to be slower than in mature beef, that fact 
would have constituted a good reason for the claim that immature veal 
digests with difficulty in the human digestive tract. The principal ad¬ 
vantage of the third method as applied to digestion mixtures lies in the 
fact that it affords an easy, rapid method of measuring amino-nitrogen 
liberation, which can not easily be measured by other methods. 
Graphic representation of resuets. —In figure 4 the results for 
amino nitrogen in experiment 32 are plotted. Most of the other curves 
obtained in this way were flatter because the rate of amino nitrogen 
liberation by trypsin 2 was slower. The curve for experiment 32 indi¬ 
cates that during the first 36 hours, approximately, the veal digested 
