TRYPTIC DIGESTION 39 



the same extent when excess of alcohol was added. He considered that in 

 the case of trypsin some groups have the property of coagulating milk and 

 others have the proteolytic power. 



I have tested a number of pancreatic extracts at different stages apd 

 record some of the principal results below. 



In each case sheep's pancreas was used. It was finely minced and ex- 

 tracted with two and a half times its weight of water and a Uttle chloroform. 

 The experiments were similar to Nos. 25 to 28 in technique. 



29. Pancreas extracted for two days and extract then tested. 



1 cc. trypsin, 40 cc. 0-5 % NaaCOo, 1 g. fibrin. 14-9 cc. digested in 3 hours. 



1 cc. trypsin, 40 cc. caseinogen (1-5 % in 0-5 % NaaCOg). 44-6 cc. digested in 1 hour. 



1 cc. trypsin, 40 cc. milk. 23-3 cc. digested in 0-5 hour. 



1 cc. trypsin +20 cc. milk. No coagulation in 0-5 hour. No coagulation on now adding 



an active coagulating extract, as the caseinogen had been changed (as can be seen 



above) into products which no longer give a coagulum with rennin. 



30. Pancreas extracted for l-S hours and extract then tested. 



26-4 cc. fibrin digested in 3 hours. 



41-8 cc. caseinogen digested in 1 hour. 



No coagulation of milk, but much digestion (tannic acid). 



31. Pancreas extracted for 3 days and extract then tested. 



26'7 cc. caseinogen (milk used) digested in 0-5 hour. 

 No coagulation of milk. 



32. Pancreas extracted for 3 days and extract then tested. 



31-0 cc. caseinogen digested in 0-5 hour. 

 No coagulation of milk, but much digestion. 



These four experinients show that freshly prepared aqueous extracts of 

 pancreas generally do not coagulate milk, but are very active proteolytic 

 agents, both on fibrin and on caseinogen. 



In a few cases I have found that the filtrate after three hours' extraction 

 coagulated milk rapidly, but this was exceptional. 



It has already been mentioned that Halhburton and Brodie accounted 

 for the fact that fresh extracts have very Uttle curdhng action on milk by 

 supposing that trypsin deteriorates more quickly and in a few days or weeks 

 allows the rennin to reveal its presence. Vernon seems to suggest that a clot 

 IS formed but is dissolved almost at once. In the extracts which I used, the 

 coagulating power seemed to be fully developed within 15 days, but I never 

 found the proteolytic power to diminish as rapidly as would have to be the 

 case if the above suggestion accounted for all the facts. 



The extract used in experiment 30 was tested again for proteolytic power 

 when five weeks old. Complete coagulation of milk now took place within 

 four minutes, and the amount of caseinogen digested was now 44-7 cc, this 

 being actually shghtly more than it digested at first. If in the first case a 

 clot were formed but almost immediately redissolved, this should have been 

 still more the case when the proteolytic power had increased, instead of which 

 complete coagulation rapidly took place. In other cases the milk coagulating 

 power seemed to have developed completely within four days, the proteolytic 



(505) 



