THE DIGESTIVE SYSTEM. 



247 



hung on the chain, his fore limbs trembled, he brought 

 his hind extremities as much as possible under him, and 

 bent his neck and depressed his head, and, after a deep 

 and powerful inspiration, he vomited fifteen pounds of 

 semi-fluid matter, perfectly triturated. The vomiting 

 ceased, the ox remained for a moment motionless^ and 

 then lay down again and ruminated afresh. He continued 

 thus about thirty-five minutes, when he had a renewed 

 fit of vomiting perfectly similar to the preceding." The 



Fig. 44. — (Esophageal groove, a. CEsophagus, with (h) its opening into the 

 groove, d. Mucous membrane dissected back. e. Rumino-reticular 

 sphincter. (Carpenter.) 



act of vomiting is regulated by a special centre in the 

 medulla oblongata, is reflex, and is brought about by a 

 deep inspiration fixing the diaphragm, contraction of all the 

 abdominal sphincters, and then of the abdominal muscles, 

 and of the walls of the stomach, together with reversed peri- 

 stalsis of the oesophagus. Impaction of the rumen has been 

 treated by injection of fluid until vomition took place. 

 Vomiting, too, is a symptom of foreign bodies in the reti- 

 culum, and of impaction of the oesophagus near the rumen, 

 where the knot of a straw or hay band is apt to become fixed. 



