132 VETERINARY LECTURES 



to swallow, and also acts chemically on a small pro- 

 portion of the starchy matter, converting it into sugar 

 by the action of a special ferment in the saliva. 



(4) The food, having been well masticated, is formed by the 



tongue and cheeks into a bolus, which is passed to the 

 back of the mouth, where it is seized by the action of 

 the muscles of the pharynx and pressed into the gullet, 

 down which it is propelled by the progressive con- 

 traction of the involuntary muscular fibres of that 

 canal into the stomach. 



(5) In the stomach it is mixed with gastric juice, a fluid 



of an acid character, which, again, acts chemically 

 upon it. For the better accomplishment of the 

 process, the food is being constantly rolled about, or 

 * churned,' by the action of the different muscular 

 coats of this organ. The flesh-forming matters — 

 albuminoid portions, or proteids — are here converted 

 into the more soluble peptones, and a portion of the 

 nutritive elements is absorbed and carried into the 

 portal vein, and thence to the liver ; while the rest 

 of the food is converted into a soft-soap-like material 

 called chyme. 



(6) The Chyme is next passed on into the small intestine. 



Here it is met by the bile (which the liver is constantly 

 secreting), the pancreatic juice, or intestinal saliva 

 (formed by the pancreas), and by the juices of the 

 various small intestinal glands. The pancreatic juice, 

 which is alkaline, and somewhat resembles saliva, has 

 a powerful action on fats, converting them into such 

 a form that they are capable of being absorbed, while 

 the bile assists in the emulsification of the fats. The 

 bile also appears to act as a natural purgative. 



(7) The different kinds of food having now been acted upon 



by the fluid secreted by the salivary glands and 



