104 The Feeding of Animals 



aud that the starch has been changed to a sugar or 

 other soluble bodies. In both cases substances insolu- 

 ble in water have become soluble and diffusible. 



The cause of these changes is the presence of typical 

 bodies, one in the pig's stomach and one in the malt, 

 ferments of the enzym class, the former of which ren- 

 ders albuminoids soluble, the latter acting to produce 

 a similar result with the insoluble carboh^-drates. This 

 action is different from that of the organized ferments, 

 where oxidation occurs in many cases. The enzym s 

 simply induce the albuminoids and starch to take up 

 the elements of water, which apparently does not greatly 

 diminish their energy value. How this is done cannot 

 be explained in simple terms, if at all. Our knowledge 

 of the manner of the change rests entirely upon theo- 

 retical grounds. The digestion of food is almost wholly 

 accomplished through the specific effect of enzym bod- 

 ies, of which every digestive fluid contains one or 

 more. Examples of these are the pepsin and pan- 

 creatin of the drug store that contain enzym s mixed 

 with more or less impurities. The function of each 

 of these ferments we shall consider as we proceed to 

 discuss the various steps of digestion. 



THE MOUTH 



The first step in the digestion of fodders and whole 

 grains is to reduce them to a much finer condition. 

 This is done in the mouth, the teeth being the grind- 

 ing tools.* Sometimes the cutting or grinding is par- 



*This is not true of hens, turkeys and other fowls. 



