102 PHYSIOLOGY AT THE FARM. 



portion of the ruminated aliment which goes into the first and 

 second stomachs, being mingled with the new aliment, may 

 possibly, in part, be again carried to the mouth. 



The coats of these stomachs are much the same as the 

 essential coats of the stomach in the horse that is, the outer 

 covering is a serous membrane, being a part of the general 

 shut sac of the peritoneum ; the middle coat consists of mus- 

 cular fibres ; and the internal coat is a mucous membrane, 

 covered, however, in the three first stomachs, by a cuticular 

 investment corresponding to that investment which lines the 

 cardiac half of the stomach in the horse. The fourth stomach 

 has a mucous lining, soft like that of the human stomach, and 

 thrown into folds, which are transverse at the extremity near 

 the third stomach, and longitudinal in the middle, and becom- 

 ing by degrees effaced near the intestinal opening. According 

 to Cuvier, there is no valve in the pyloric opening, but one 

 between the third stomach and the fourth. 



These stomachs are abundantly supplied with blood by arte- 

 rial branches derived from the posterior aorta. The arteries 

 of the stomach have a course corresponding to that already 

 described as observed in the horse (p. 41). The veins enter 

 into the formation of the portal vein, or that great peculiar 

 vein which, formed from the veins of the organs in the abdo- 

 men concerned in digestion, enters the liver for the purpose, 

 as is believed, of supplying the secretion of the bile. The 

 nerves of the stomach in the ox, like those of the horse, are 

 derived from the terminal branches of the pneumo-gastric 

 nerves of the eighth cranial pair, together with offsets from 

 the solar plexus of the sympathetic nerve. 



Process of Digestion in the Stomachs of the Ox. The general 

 observations made under the head of stomach-digestion in the 

 horse, apply equally to stomach-digestion in the ox (p. 42). The 

 body of the ox consists of the same fifteen simple elements, all 



