THE STOMACH. 199 



a The oesophagus oy gullet, extending to the stomach. 



b The entrance of the gullet into the stomach. The circular layers of the mucsles are 



very thick and strong, and which, hy their contractions, help to render it difficul 



for the food to be returned of vomited. 

 c The portion of the stomach which is covered by cuticle or insensible skin. 

 d d The margin wliich separates the cuticular from the villous portion. 

 e e The mucous or villous (velvet) portion of the stomach, in which the food is principally 



digested. 

 f The communication between the stomach and the first intestine. 

 g The common orifice through which the bile and the secretion from the pancreas pass 



into the first intestine. Tlie two pins mark the two tubes here united. 

 k A smaller orifice, through which a portion of the secretion of the pancreas enters the 



intestines. 



The orifice by which the gullet enters the stomach is called the cardiac^ 

 5, from its nearness to the heart, or sympathy with it. It is constantly 

 closed by strong muscular fibres, except when food is passing into the 

 stomach. It is the construction of the soft palate, however, as has been 

 already described, and not this closing of the cardiac orifice of the stomach, 

 that chiefly prevents the act of vomiting in the horse. 



The stomach has four coats. The outermost is the lining of the cavity 

 of the belly, and the common covering of all the intestines ; by which they 

 fire all confined in their respective situations, and from which a fluid is 

 given out, which prevents all friction between them. This is called the peri- 

 ioneu7n, or that which stretches round. 



The second is the muscular coat, consisting of two layers of fibres, one 

 running lengthways, and the other circularly, and by means of which a 

 constant gentle motion is communicated to the stomach, by which the food 

 is more thoroughly mixed together, and prepared for digestion, and by the 

 pressure of which also the food when properly prepared is pushed on into 

 the intestines. 



The third, or cuticular, {skin-like coaQ c, covers but a portion of the 

 inside of the stomach. It is a continuation of the lining of the gullet. 

 There are numerous glands on it, which pour out a mucous fluid ; and it 

 is, probably, intended to be a reservoir in which a portion of the food is 

 retained for a while, and softened and better prepared for the action of the 

 other or true digestive portion of the stomach. The cuticular coat occupies 

 nearly one half of the inside of the stomach. 



The fourth coat is the mucous or villous (velvet) coat, e, where the work 

 of digestion properly commences. The mouths of numerous little vessels 

 open upon it, pouring out a peculiar fluid, the gastric (stomach) juice, 

 which mixes with the food already softened, and converts it into a fluid 

 called chyme. As this is formed, it passes out of the other orifice of the 

 stomach, the pyloric, (a door to guard,) /, and enters the first small intes- 

 tine ; the harder and undissolved parts being turned back to undergo 

 further action. 



The stomach of the horse being small, this wonderful change which is 

 effected in the food, and the nature of which has never been thoroughly 

 undei-stood, proceeds very rapidly. The horse, in a short time, will eat a 

 great deal more than the stomach will hold, and room can only be made 

 for the reception of the fresh food by that which had been previously re- 

 ceived being discharged through the pyloric orifice. 



Of one disease of the stomach, arising from over distension, stomach- 

 staggers, we have already spoken. In a few instances the stomach has 



