i8o 
BUIvLETiN OE THE BUREAU OF FISHERIES. 
The amino nitrogen in solution increases of course with length of time. The aver- 
age size of the peptids split off from the protein should be especially noted. From 
these data and the experiments of White and Crozier it is evident that the proteins 
studied break down into simple cleavage products practically as soon as they go into 
solution. At the end of a half hour’s digestion the average size of the peptids is only 
2.02; the cleavage products on the whole are indicated to be amino acids. The cleav- 
age of certain proteins by trypsin has been intimately studied, and it is known that 
some amino acids 
are readily formed, 
while others are pro- 
duced slowly or not 
at all. The above re- 
sults, however, show 
that the greater por- 
tion of the nitrogen 
in solution exists in 
bodies of exceed- 
ingly simple char- 
acter. The signifi- 
cance of this physio- 
logically can not be 
pointed out here,but 
will be reserved for 
future discussion. 
The relation of 
the amino to the to- 
tal soluble nitrogen 
is shown in figure 2 . 
After eight hours’ 
digestion only 28.35 
percent of the nitro- 
gen is in the amino 
form. This is a con- 
firmation of earlier 
work which, as just mentioned, has shown that there are certain substances which resist 
the hydrolytic action of trypsin altogether. The increase in the proportion of amino 
nitrogen during the eight hours’ digestion is very slight, and we must conclude, there- 
fore, that the cleavage of the meat, while yielding amino bodies of a simple nature, 
leaves the greater part of the soluble nitrogen combined in substances which are 
extremely stable. 
The same conclusions may be drawn from the results of our experiments involving 
Sorensen’s method. In figure 2 the curves are of the same slope, although, of course. 
T/he'f/f 
b^urj 
.Fig. I. — Change of the per cent of soluble nitrogen of the total nitrogen during the time of 
proteolysis. 
