162 THE WORK OF THE DIGESTIVE GLANDS. 



Mett's tubes in from three and a half to six minutes. That is to say, 

 the juice was an extremely active one. The same result was obtained 

 with the juice which first flowed from a permanent fistula. Our in- 

 terest in the normal variations of digestive power of the juice and in their 

 possible dependence upon diet, therefore, became still greater, because 

 in this way we hoped to be able to discover the meaning of the remark- 

 able relationships in question. As a matter of fact, we found that, in 

 dogs fed exclusively on flesh, the zyrnogen condition of the fei'ment 

 almost wholly disappeared after a short time. The juice contained 

 then only trypsin, and the succus entericus had no augmenting effect. 

 Indeed, on the contrary, for some reason or other it often slightly 

 diminished the proteolytic action of the fluid. With dogs, however, 

 which were fed chiefly on starch and fat (bread, milk, and so on) the 

 gland furnished a juice with a very weak initial effect upon proteids, 

 the action of which was rendered very energetic by an addition of 

 succus entericus. Obviously the zymogen stage of the ferment predomi- 

 nated here. Consequently, the appearance of the proteolytic ferment 

 under different forms depends upon definite conditions. The idea at 

 once occurred to us that, in the case of starchy and fatty foods, the 

 proteicl fei'ment is excreted in a latent form, with the object of protect- 

 ing the amylolytic and fat-splitting ferments, which might possibly be 

 injured by the other in its ripe and very active form. The experiments 

 of E. A. Hanicke have, indeed, confirmed this. A juice, mainly con- 

 taining zymogen, preserves the activity of its ferments even after 

 several hours in the thermostat, while one which has been actuated by 

 succus entericus, or contained trypsiu to begin with, has its ferments, 

 especially the amylolytic and fat-splittirig, very easily destroyed. It is 

 significant that such a protection of the ferments is chiefly required in 

 the gland-lumen and along the passage to the digestive canal. In the 

 bowel, however, where the proteicl ferment is made active by the kinase, 

 new conditions arise which protect the fat-splitting and starch ferments ; 

 namely, the presence of proteid food and of bile. This latter was 

 proved also by the experiments of E. A. Hanicke. 



It was further shown that the promoting effect of bile upon the fat- 

 splitting ferment likewise depended on definite conditions of diet. 

 The relationships of the amylolytic ferment were, however, less obvious 

 in this respect. Additional experiments are also desirable, and indeed 

 necessary, to investigate the fact that an antagonism was often observed 

 between albumen on the one hand, and the actuating influences of the 

 succus entericus and the bile on the other. 



Thus, the newly discovered kinase soon found useful employ- 

 ment. But whether, under similar circumstances, the augmenting 

 action of spleen extract upon infusions of the pancreas first observed 



