TRYPTIC DIGESTION 



33 



the filtrate by Kjeldahl's method. Control experiments were always carried 

 out at the same time. 



In the above experiments it will be seen that even in acid solution the 

 pancreatic extracts used generally lost practically all their power to digest 

 fibrin even when heated only to 60° for a minute and a half. The power to 

 digest caseinogen was not so completely lost, especially in the last three 

 experiments, but it was so markedly reduced, compared with what had been 

 previously found, that the matter merited further investigation. 



The extracts used above were aqueous, so a few experiments were carried 

 out to compare the effect of heat on aqueous and alcohohc (20 %) extracts 

 of the same pancreas. The experiments were carried out in the same way 

 as those previously noted. 



It will be seen that the alcohohc extracts retain very much more of their 

 power to digest fibrin after being heated than do the corresponding aqueous 

 extracts. The amount of protein and other nitrogenous substances was 

 practically the same in the two sets of extracts. It might be supposed that 

 the alcohol itself in some way protected the trypsin from destruction when 



(499) 



