336 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



has been noticed to take place in the horse. Under such circumstances 

 it is a symptom of the greatest gravity, and in most cases it will be 

 found to be due to the partial rupture of the walls of the oesophagus. 



Ruminants, also, habitually do not vomit, but do so occasionally. 

 When the structure of the stomach of the ruminant animal is examined, 

 all the conditions would at first appear to favor vomiting. The gullet is 

 large, dilatable, and has a funnel-shaped opening into the stomach ; the 

 stomach is large, is in direct contact with the abdominal walls and the 

 diaphragm, and the pylorus is far removed from the cardiac orifice. 

 Nevertheless, vomiting, even when intense nausea is produced by emetics, 



FIG. 144. ANTERIOR HALF OF THE STOMACH OF THE HORSE, INFLATED, 

 SEEN FROM BEHIND. (MUller.) 



Sch, oesophagus ; G, cardiac cul-de-sac ; kC, lesser curvature ; gC, greater curvature ; 1 A, mucous 

 membrane of the left half, and rA, mucous membrane of the right half of the stomach: R, dividing line 

 between right and left halves of the stomach ; F, fold projecting into stomach from the lesser curvature ; 

 L, peptic region ; Sch.1, mucous region ; gMs, muscular pillars surrounding the opening of the oesophagus ; 

 d, section of the muscular fold ; P, pylorus ; PH, pyloric cavity : E, constriction separating pyloric por- 

 tion from right half of stomach ; Z, duodenum ; Erw, pear-shaped dilatation of duodenum ; M, opening 

 of the bile and pancreatic ducts. 



will but rarely take place, and w r hen vomiting does occur in these 

 animals it is the contents of the rumen and reticulum alone which are 

 expelled, while true vomiting should require the escape of the contents 

 of the fourth stomach. To enable this to take place, the material from 

 the fourth stomach would have to pass through the narrow openings of 

 all the three preceding stomachs. When matters are ejected from the 

 stomach through the action of emetics in a ruminant animal, if at all, 

 the contents of the rumen alone are ejected, and these ma}^ be again 

 swallowed, as in rumination, without escaping from the mouth. 



