MAMMALIA. 679 



nary gastric secretions, and appears to be more especially the di- 

 gestive stomach. 



The passage of the food through these different chambers will 

 be easily understood on referring to the preceding figure, in which 

 the course of the aliment before and after rumination is indicated 

 by the direction of the probes a, b. The oesophagus, it will be 

 observed, communicates on the one hand with the paunch d, and 

 on the other with the cavities c, e,jf; and, moreover, by means 

 of a muscular fold formed by the walls of the second cavity, a pas- 

 sage may be formed leading directly into the third stomach (e) 

 without communicating with the second (c). The process of 

 rumination would, therefore, seem to be effected in the following 

 manner. The herbage when first swallowed in an unmasticated 

 condition passes into the capacious paunch (rf), where it accu- 

 mulates, and undergoes, no doubt, a kind of preliminary mace- 

 ration. When the RUMINANT has done grazing, and is at lei- 

 sure, the food is again regurgitated into the mouth, to undergo 

 more careful and complete mastication : for this purpose, a part of 

 it is admitted into the reticulum (c), and there formed into a 

 smooth and lubricated bolus ; which, being expelled into the oeso- 

 phagus, is immediately seized by the spiral muscles surrounding 

 that canal, and forced forwards into the mouth. After undergoing 

 a thorough triturition, the aliment is once more swallowed, and 

 it then enters into the third stomach e, passing along the muscular 

 fold that leads from the oesophagus into that compartment. 

 Here it is spread out over the extensive surface formed by the 

 laminated walls of the psalterium, and is prepared for admission 

 into the last cavity f, which, as has been said, is the true digestive 

 stomach. 



(764.) While the young Ruminant continues to be nourished by 

 its mother's milk, the three first cavities are undeveloped and com- 

 paratively very small ; so that the milk passes on immediately 

 into the fourth stomach, to be at once appropriated as aliment. 



(765.) In the Camel, the Dromedary, and the Llama, the 

 walls of the reticulum and of a portion of the paunch are ex- 

 cavated into deep cells or reservoirs bounded by muscular fasci- 

 culi, wherein water may be retained in considerable abundance, un- 

 mixed with the contents of the stomach ; it is in consequence of 

 this arrangement that these animals are able to subsist for many 

 days without needing a fresh supply of water even during long 

 journeys in a tropical climate. 



