108 THE FEEDING OF ANIMALS 



It has been asserted that the bile has more or less 

 antiseptic influence and so prevents the intestinal con- 

 tents from undergoing putrefactive fermentation. A 

 more rational explanation is that because the bile acts as 

 a natural purgative the food residues pass promptly out 

 of the intestinal tract before the putrefactive fermenta- 

 tions set in which would occur in the absence of bile. 



153. The pancreatic juice. This secretion has the 

 most comprehensive action on the food nutrients of any 

 one of the intestinal liquids. It originates in the pancreas 

 (sweetbread). Its flow is intermittent, being induced by 

 the reaction especially of the acids in the partially digested 

 foods from the stomach. The amount secreted and 

 its composition appear to change with the kind of food. 

 It contains with the horse about 98.2 per cent of water 

 and 1.8 per cent of solid matter. With the dog the per- 

 centage of water is about 90. This secretion acts upon all 

 classes of nutrients, as it contains a variety of ferments 

 greatly unlike in function. 



154. The enzyms of the pancreatic juice. The three 

 enzyms present in the pancreas secretion are: a protein- 

 splitting enzym, trypsin (or its progenitor), a starch- 

 splitting enzym, amylopsin, and a fat-splitting enzym, 

 steapsin. Trypsin, like pepsin, hydrolizes the protein by 

 progressive stages to proteoses, then peptones, after 

 which, in conjuction with erepsin (see later), breaks the 

 peptones into simpler bodies known as the amino acids. 

 (See Par. 84.) Trypsin acts in neutral or in alkaline solu- 

 tions, a free mineral acid like hydrochloric completely 

 stopping its operation. Organic acids, like lactic, do not 

 seem to have this effect. 



155. Steapsin. The pancreatic secretion acts vigor- 

 ously on fats, not only splitting them into fatty acids and 



