DISEASES OF THE DIGESTIVE SYSTEM. 549 



The next process of digestion is deglutition, or swallowing. I need hardly say, that with 

 our canine friends this is not a very protracted one. 



Received into the stomach, the real work of digestion begins. This is called by 

 physiologists, chimification. The stomach keeps the food constantly in motion, so that every 

 portion of it, in regular rotation, is brought into contact with the walls of the viscus, and is 

 thus mixed with the secretions from the follicles the gastric juice. This fluid is acid, and 

 contains pepsin, which, with the acid, has the power of dissolving the albuminous, gelatinous, 

 and saccharine portions of the food. Not, however, the oleaginous ; that is reserved for lower 

 down. 



One thing with regard to this juice should be borne in mind, as it has a bearing on the 

 feeding of dogs : the gastric juice can only dissolve a limited portion of food at a time. Any 

 superabundance with which the animal may have gorged himself will ferment, and become a 

 source of irritation to the nerves and stomach, and prevent the animal from enjoying good 

 health or sound sleep ; and it is a well-known fact that house-dogs that are sparingly fed 

 always thrive best. 



The food when dissolved and mixed with the gastric juice is called chyme, and escapes 

 into the intestine through the pyloric opening. 



And then begins the process of chylification, or intestinal digestion. The chyme, still 

 kept in motion by the walls of the intestine, is mixed with the bile, the pancreatic juice, and 

 the secretions from the follicles. 



The bile from the liver saponifies the fatty portion of the food, and renders it fit for 

 absorption by the intestinal villi. The pancreatic juice is somewhat similar to the saliva, and 

 has similar functions, while at the same time it assists the liver in its duties. 



The intestinal secretions, like the gastric, dissolve albuminous substances, and convert 

 starch into sugar. 



The good portion of the food converted into chyle is separated from that which is unfit to 

 be made into blood, and taken up by the absorbents of the villi. The contents of the bowels 

 are being continually whirled onwards by the alternate contraction and dilation of the circular 

 muscular fibres that surround it, these muscles forming, so to speak, a sort of intestinal police 

 force that are continually ordering them to "move on." 



There are what we call lacteal vessels, rising from the intestine ; these lacteals originate 

 in the absorbents of the villi, which have sucked up to use familiar language the chyle from 

 the food. And this milky-looking chyle is carried along through the mesenteric glands, and 

 poured into a kind of reservoir which lies near the aorta, and which also receives the contents 

 of another set of vessels, called the lymphatics, with which at present we have nothing to do. 

 Upwards, then, from this reservoir of chyle there passes a larger vessel, named the thoracic 

 duct. Right in front of the spine runs this duct, bearing along its nutritious load, until it 

 comes to near the extremity of the jugular vein, and here it pours its contents into the blood. 

 The reservoir for the chyle is, in the dog, very large. By a process of endosmosis there is 

 also direct absorption of fluids through the walls of the stomach into the capillary vessels of 

 the villi. 



Let us now consider the ailments of this great canal. 



I. Dyspepsia. 



Dyspepsia, or indigestion, is one of the commonest of all diseases in non-sporting, and 

 especially in pampered or petted dogs. Sporting dogs are like sporting men, they seldom want 



