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, and smallest, cavity, 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 (abomasus), 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 

 O3sophagus 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- 

 ers of fibres, running length- 

 wise, around and obliquely. The 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 



PIG. 57. Vertical Section of the 

 Coats of the Stomach: 1, surface 

 of mucous membrane, and mouths 

 of gastric follicles ; 2, gastric tubu- 

 li, or follicles ; 3, dense connective 

 tissue ; 4, sabmucous tissue ; 5, 

 transverse muscular fibre ; 6, longi- 

 tudinal muscular fibre ; 7, fibrous, 

 or serous, coat. 



