INTERNAL PANCREATIC SECRETION 103 



erine and the fatty acid corresponding to the kind of fat which is 

 split up. In the intestine it is probable that only a part of the 

 neutral fats are thus split in glycerine and fatty acids. The 

 fatty acids thus formed unite with the alkaline salts to form soaps, 

 and these soaps, aided by intestinal peristalsis, convert the 

 remaining fats into an emulsion. The products of fat digestion 

 are therefore glycerine, soaps, and emulsions, all of which can 

 be absorbed in a way to be noted later. While the emulsification 

 of fats under the influence of soaps (fatty acids and alkaline salts) 

 is an undoubted effect, the method of procedure is unknown. 

 It is certain that the emulsification is aided by the presence of 

 bile, although this fluid possesses no fat-splitting enzyme. 



Method of Secretion. It can be shown that the secretion 

 begins to be discharged into the duodenum very soon after the 

 entrance of food into the stomach, and continues as long as 

 intestinal digestion is in progress. Consequently the flow will be 

 intermittent if the meals are far enough apart. It is almost 

 certain that the secretion is a reflex act as a result of impressions 

 upon the mucous membrane of either the stomach or the duo- 

 denum. The acidity of the gastric juice seems to be the natural 

 stimulus and to exert its influence upon the duodenal mucous 

 membrane. This is not incompatible with the early flow after 

 the ingestion of food, for it will be seen later that at least a small 

 quantity of that food passes quickly to the duodenum and carries 

 gastric juice with it. The composition of the secretion seems to 

 be influenced in some degree by the character of the food. It is 

 interesting that oils increase the pancreatic flow. 



Nerve Supply. The pancreas has, besides vaso-motor fibers 

 to its vessels, distinct secretory fibers, like those of the salivary 

 glands. These fibers probably run in both the sympathetic and 

 the vagus. 



Internal Pancreatic Secretion. Circumstantial evidence 

 leaves scarcely any doubt that the pancreas produces some sub- 

 stance which is discharged into the blood and markedly influ- 



