434 



MAMMALIA— PHYSIOLOGY 



tions. The cow moves her lower jaw once in one direction and then 

 chews the other way. Subsequent to mastication the food is swal- 

 lowed again and passes through rumen and reticulum to the omasum 

 or psalterium. 



The omasum or psalterium, sometimes called " the maniplies," 

 has loo longitudinal folds or laminae which spring from its dorsal 

 and lateral walls. A dozen of the largest have a convex attached 

 edge and a free concaved ventral edge. The food is pressed into 



ReHculum 



Abomasum 



Dorsal sac -4 



—;/■ Duodenum 



' Posterior blind sacs 



Fig. 241. Stomach of a ruminant. (Drawn by W. J. Moore.) 



thin layers in the spaces between the laminae and reduced to a fine 

 state of division, by being ground down by minute horny papillae 

 studding the surface of the folds. From the omasum the food passes 

 into the true stomach. 



The abomasum^ or true stomach, is divided by a constriction into 

 two regions, the fundus and the pylorus. It has a mucous coat and 

 longitudinal and circular muscles, strongly developed to form the 

 pyloric sphincter. In the abomasum the acid gastric juice functions 

 as in other mammals. 



References on the Ruminant Stomach 



Reynolds, M. H. 191 i. Veterinary Studies for Agricultural Students. 



Macmillan and Co., N. Y. 

 ScHALK, A. F., AND Amadon, R. S. 1928. PHysiology of the Ruminant 



Stomach. Bull. 216, North Dakota Agr. Exp. Sta., Fargo, N. D. 

 SissoN, S. 1914. Anatomy of Domesticated Animals. 2d ed. W. B. 



Saunders Co., Phila. 



