VELOCITY OF REACTION. HOMOGENEOUS SYSTEMS 77 



As we have seen above, the albumose-salts produced in 

 the digestion exert an enormous retarding influence on 

 the velocity of digestion. In the same manner according 

 to Sawjalow the addition of peptone to a mixture of milk 

 and gastric juice increased the time of coagulation to a 

 notable degree. This time, for instance, increased from 

 29.8 seconds to 791 seconds on the addition of 4 c.c. of 

 peptone solution (i c.c. was equivalent to 5.5 mg. HC1) 

 instead of 4 c.c. of water to a mixture of i c.c. stomachal 

 fluid with 10 c.c. of milk. The action was therefore dimin- 

 ished to about 4 per cent. A like influence is exerted by 

 peptone solution on the velocity of reaction on milk of 

 pancreatic juice or of solution of papayotin. 



As peptone is very nearly related to albumose, this 

 seems to indicate that the digestive action of pepsin is 

 identical with the coagulating influence of rennet or pan- 

 creatic liquid or papayotin, as Pawlow and Sawjalow have 

 contended. A substance that acts in a similar manner to 

 pepsin on thymolgelatin is trypsin. On the action of dif- 

 ferent quantities (from 0.0022 to 0.3 c.c.) at 47.3 C. the 

 following investigations were carried out by Madsen and 

 Walbum. In this case no acid was added to the liquid in 

 the test-tubes, but only 2 c.c. of thymolgelatin, q c.c. of 

 trypsin solution, and (2 q) c.c. of I per cent salt solution. 

 These investigations indicate that in this case, as well as in 

 those treated above, the product of the time of reaction 

 and reacting quantity is a constant, if the magnitude of 

 reaction is the same. In the following table the signs / 

 and q denote time and quantity: 



