THS ACT OP RUMINATION. 381 



second stroke, and all those whicli follow it until the bolus 

 is sufficiently masticated, takes place from right to left, or 

 in the opposite direction to that of the first. While the 

 mastication is going on, fresh quantities of saliva are 

 poured into the mouth, and when the grass is thoroughly 

 ground up, the semifluid product is passed back into the 

 pharynx and swallowed once more. These actions are 

 repeated until the greater portion of the grass which 

 has been cropped is pulpified. 



The precise nature of the operation, the external features 

 of which have now been described, has been the subject of 

 much investigation and discussion. The following points 

 appear to have been clearly established : 



1. Rumination is altogether prevented by paralysis of 

 the abdominal muscles, and it is a good deal impeded by 

 any interference with the free action of the diaphragm. 



2. Neither the paunch, nor the reticulum, ever becomes 

 completely emptied by the process of regurgitation. The 

 paunch is found half full of sodden fodder, even ia animals 

 which have perished by starvation. 



3. "When solid substances are swallowed, they pass indif- 

 ferently into the rumen, or reticulum, and are constantly 

 driven backwards and f oi-wards, from the one into the other, 

 by peristaltic actions of the walls of the stomach. 



4. Fluids may pass either into the paunch and the re- 

 ticulum ; or into the psalterium, and thence at once into 

 the fourth stomach, according to circumstances. 



5. Rumuiation is perfectly well effected after the lips 

 of the (Esophageal groove have been closely united by wire 

 sutures. 



It would appear, therefore, that the cropped grass passes 

 into the reticulum and rumen, and is macerated in them. 

 But there is no reason to believe that the reticulum takes 

 any special share in modelling the boluses which have to be 

 returned into the mouth. More probably, a sudden and simul- 

 taneous contraction of the diaphragm and of the abdominal 

 muscles, compresses the contents of the rumen and reticulum, 

 and drives the sodden fodder against the cardiac aperture of 



