TIIE 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 
oesophagus 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 
Fig. 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, submucous tissue; 5, 
transverse muscular fibre; 6, longi¬ 
tudinal muscular fibre ; 7, fibrous, 
or serous, coat. 
