STOMACHS OF THE SHEEP. 297 



digestion glide overtheniw But most of the food of the*heep, 

 like that of other ruminating animals, is swallowed with little 

 preparatory mastication ; and these vmtriturated solids drop 

 down through the first opening alaove described into the 

 rumen. It is certain, however, that the animal can, at wUl, 

 also cause water to pass through the opening into the first 

 stomach. This would be necessary in the animal economy, 

 and the water is always found there. 



"When the food has -entered the rumen, the muscular 

 action of that viscus compels it to make the circuit of its 

 different compartments, and, in time, the food later swallowed 

 forces it on and up to near the Opening wheje it originally 

 entered. In its passage it is macerated by a solvent alkaline 

 fluid secreted by the mucous coat. The papillae of that coat 

 are supposed to influence the mechanical action of the 

 contents of the stomach, and, perhaps, to a certain extent, to 

 aid in triturating them. The food performs the circuit of the 

 stomach, and is ready for re-mastication, according to 

 Spallanzani, in from sixteen to eighteen hours. By a 

 muscular effort of the stomach, a portion of it is then thrown 

 over the membraneous valve or. fold which .guards the 

 opening from this into the second stomach. The reticulum 

 contracts upon it, forming it into a suitable pellet to be 

 returned to the mouth, and also covers it with a mucus 

 secreted in this stomach. By a spasmodic effort (always 

 perceptible externally when the sheep or cow commences 

 rumination) the pellet is forced through the roof of the ' 

 reticulum, by the opening before described, and returned to 

 the mouth by contractions of the spiral muscle of the 

 esophagus Or gullet, for mastication. 



" This explanation of the functions of the second stomach 

 is not accepted by all the physiologists who have examined 

 this subject. Some contend that all the solider portions 

 of the food are returned directly from the rumen for 

 re-mastication ; that when raised to the floor of the esopha- 

 gean canal, the hard parts are carried up to the mouth. — the 

 more pultaceous ones (but still not sufiiciently pultaceous 

 for the fourth stomach) passing into the reticulum, where 

 they are again macerated — the fluid squeezed out of them 

 by a contraction of the stomach and allowed to pass on to the 

 fourth stomach — and then the drier parts raised, like thosei 

 from the paunch, for re-mastication. More solid and indi- 

 gestible substances ' may be submitted two or more times to 

 the process of rumination.' " 

 13* 



