THE ALIMENTARY CANAL. 



89 



hence it is sometimes called the water -bag. Here the 



food is made into little balls, and returned to the mouth 



to undergo a thorough mastication. When finally swal- 



lowed, it is directed, by a groove from the oesophagus, to 



the third, arid smallest, cavit\ r , the manyplies (psalterium\ 



named from its numerous folds, which form a strainer to 



keep back any undivided food; and thence it passes into 



the true stomach (dbom-asus), from which, in the calf, the 



rennet is procured for curdling milk in the manufacture 



of cheese. This fourth cavity 



is like the human stomach in 



form and function, and is the 



only part which secretes gastric 



juice. The rumen and reticu- 



lum are rather dilatations of the 



ossophagus than parts of the 



stomach itself; while the latter 



is divided by constriction into 



two chambers, the psalterium 



and abomasus, as in many other 



animals. 



In structure, the stomach re- 

 sembles the oesophagus. The 

 smooth outside coat (perito- 



, ^ 



neum) is a reflection of the 

 ..... , , , 



membrane which lines the whole 

 abdomen. The middle, or mus- 

 cular, coat consists of three lay- 



FIG. 57. Vertical Section of the 

 Coats of the Stomnch: 1, surface 

 of mucons membrane, and mouths 



,f gas tnc follicles; 2, gastric mim- 



ers of fibres, running length- or serous, coat. 

 wise around and obliquely. "Fhe successive contraction and 

 relaxing of these fibres produce the worm-like motion of 

 the stomach, called peristaltic. The innermost, or mucous, 

 membrane, is soft, velvety, of a reddish-gray color in Man, 

 and filled with multitudes of glands, which secrete the 

 gastric juice. The human stomach, when distended, will 



