112 The Feeding of Animals 



ment it is in a very finely -divided condition and is 

 thoroughly prepared for the action of the juices that 

 are subsequently poured upon it. 



It is at the last stage of the journey of the food 

 through this complicated stomach that it is submitted 

 to the true gastric digestion. As a matter of fact, the 

 abomasum or rennet is regarded as the true stomach, 

 the other three sacs being considered as enlargements of 

 the oesophagus. In the calf, the rennet is the only part 

 developed, the other divisions not coming into use 

 until the animal takes coarse foods in considerable 

 quantity. The fourth stomach is larger than either 

 the second or third. It receives directly from the 

 omasum the finely divided food, upon which it pours 

 the gastric juice, a liquid that is secreted in large 

 quantity by glands located in its inner or mucous 

 membrane. This juice, like all the digestive fluids, 

 is mostly water, the proportion being between 98 

 and 99 parts to less than two parts of solids. The 

 latter consist of ferments, a certain amount of free or 

 uncombined hydrochloric acid and a variety of mineral 

 compounds, prominent among which are calcium and 

 magnesium phosphates and the chlorides of the alka- 

 lies, common salt being especially abundant. 



Especial interest pertains to the ferments of the gas- 

 tric juice, one of which, in connection with free hydro- 

 chloric acid, causes a most important change in the . 

 proteids of the food by reducing albuminoids, such as 

 the gliadin and glutenin of the wheat kernel to soluble 

 forms. We know quite definitely about this action, 

 because it can be very successfully produced in an ar- 



