332 BACKBONED ANIMALS. 
food or cud is chewed twice before it is finally digested.* 
The molar teeth have two double, crescent-shaped folds, 
and, in biting, the incisors of the lower jaw are pressed 
Fic. 356.—Stomach of a ruminant (sheep): @, cesophagus; Az, paunch; 
ret, honey-comb; Ps, manyplies; @, true digestive stomach or rennet; 
au, beginning of intestine. 
against the opposite and toothless gum of the upper. The 
stomach (Fig. 356), with few exceptions, is divided into 
four compartments: 1. The paunch, rz; 2. The honey- 
* The grass, partly chewed and mixed with saliva, is swallowed, 
and passes into the cesophagus; the latter is continued into a tube 
with a long slit on its under side, whose lips fit closely, and are 
water-tight. The tube thus formed leads naturally to the third stom- 
ach, and here we see a wonderful provision. The coarse food as it is 
swallowed at first, from its size presses open the slit, and drops into 
stomach No. 1, or paunch, where it is mixed with water. From here it 
goes into stomach No. 2, or the honeycomb, where the polygonal spaces 
may serve to fashion it into pellets or cuds. Now, by a simultaneous 
contraction of the diaphragm and abdominal muscles, a cud is forced 
against the cardiac aperture of the stomach into the cesophagus, and so 
into the mouth, where it is chewed by the molar teeth, and again swal- 
lowed at last ready for digestion. As it passes down for the second 
time, we would perhaps expect it to press open the slit and drop into 
the first stomach again ; the second chewing, however, has reduced it 
to a pulp, so that it is now not large enough, and it passes along the 
tube over the slit and into the third stomach or manyplies, where it 
is strained ; then passing into the true stomach, where it is mixed with 
the gastric juice and absorbed. 
