FUNCTIONS OF THE BILE. 157 



extractives of meat, and the products of the digestion of egg-albumen, 

 set up a free discharge of the fluid. The bile, therefore, resembles other 

 digestive juices in that it possesses its own particular combination of 

 excitants, which have the effect of causing it to flow into the intestine. 



But in what does the work of the bile consist ? In order to answer 

 this question, which now took a definite shape, we adhered to certain 

 facts which, it must be admitted, do not enjoy great popularity amongst 

 physiologists. The lack of esteem from which they suffer is shown by the 

 fact that in many text-books of physiology they are consigned to small 

 print. The bile possesses only a weak direct chemical action upon the 

 food constituents. Different investigators have long ago shown that 

 it has a slight amylolytic action. In addition, during the past year, 

 Dr. Gegaloff discovered in this laboratory that the bile of carnivora also 

 contains a proteolytic ferment, but its action is only a weak one. We 

 are now engaged, however, in systematically examining the variations of 

 this ferment and the relationships which they bear to digestive activity. 



There remains the possibility of a chemical effect upon the other 

 digestive juices with which the bile mixes in the intestinal canal. It 

 has long been known that the ferments of the stomach and pancreas 

 manifest different degrees of digestive activity, according to the 

 chemical properties of the medium in which they work. Further, 

 there are very old experiments which point to an inhibitory action of 

 the bile upon, the ferment of the gastric juice. But, on the other hand, 

 investigations, begun originally by Professor Nencki in his Berne 

 laboratory and carried on by Heidenhain, Rachford, Williams and 

 Martin, have shown that the bile has a favouring action on the fer- 

 ments of the pancreatic juice. The majority of these experiments 

 dealt, however, with extracts of the pancreas, and consequently in the 

 main with zymogen and not with the ready-made ferment. It was 

 open, therefore, to doubt whether they would hold good for the actual 

 conditions of digestion. Bachford alone carried out experiments with 

 ferments, but n^t with all of them, and only with those of the pancreatic 

 juice of the rabbit. We shall see that in the favouring action of bile 

 upon the ferments of pancreatic juice we have discovered the main 

 feature of its digestive importance. Numerous experiments on dogs, 

 systematically carried out, have shown us that when a definite quantity 

 of bile, which varies for the different ferments, is added to pan- 

 creatic juice, it produces a constant and decided accentuation of the 

 activity of its enzymes. The effect was most pronounced on the fat- 

 splitting ferment, the action of which was increased two to three 

 fold, less on the other two, which were only increased about twofold. 

 Further, it was observed that this augmenting action showed adaptive 

 variations dependent upon the nature of the food. The bile, indeed, 



