ORGANS OF DIGESTION. 323 



Externally this organ is somewhat conical in shape, its 

 apex being the part which joins the intestines. It possesses 

 three coats, like the other stomachs ; but its internal surface 

 is very different, being smooth and shining, and of a pale red 

 color. Its mucous membrane is, indeed, very vascular, and 

 ihis secretes the gastric juice.' The internal surface is greatly 

 increased, and exceeds the, external, by being in the form of 

 plaits, arranged longitudinally, but very different from those 

 found in the manii)lus. The entrance to this stomach (its 

 jardiac opening) is close to the entrance to the maniplus ; it 

 <s arranged somewhat in a crescentic, form, and is situated at 

 one extremity of the base, whilst the pyloric opening, leading 

 into the small intestines, is, as before observed, situated at 

 the apex. Having thus described the situation and appear- 

 ance of the stomachs, an external view of which may be seen 

 at page 326, we must return to the consideration of the course 

 of the food through them. 



The situation, the structure, _and the size of the rumen 

 point it out as the first and general receptacle for the food, 

 which receives in the mouth only sufficient mastication to 

 enable the animal to swallow it. It is then received by the 

 rumen, and morsel after morsel is taken until this viscus is com- 

 paratively full. The animal then feels some repletion, and 

 rumination usually takes place, the animal generally prefer- 

 ring a recumbent posture. It has been shown, however, 

 that it is not the food just taken, but that which has been 

 swallowed some twelve or sixteen hours previously, that un- 

 dergoes the ruminating process. The food, indeed, is turned 

 and shifted about the stomach by its muscular action, and 

 ■well mixed with the fluid secreted by its internal surface : 

 it, of course, enters at first the superior compartment, from 

 which it passes to the inferior, and again enters the former 

 division ere rumination takes place. A tolerably full stom- 

 ach is necessary for the act ; for it has been found in sheep 

 that had fasted for several days that a tolerable portion of 

 foodstill remained in the rumen. Before rumination can take 

 place it is evident that the food must rise to the upper part 

 of the viscus and enter the cesophagean canal. What, then, 

 is its direction ? The liquid portion passes on in the course 

 of the canal ; but it is contended by some physiologists that 

 the second stomach, the reticulum, is the active .agent in ru- 

 mination, and that the food enters it previous to its being re- 

 turned to the mouth, and they are supported in this opinion 



