116 RUMINATION. INTESTINAL CANAL. 



paunch and honeycomb returns into the mouth, there to be 

 chewed, it has generally been attributed to the action of the 

 second stomach itself, which has been supposed to take hold of a 

 portion of the alimentary mass, to compress it so as to form a 

 rounded ball or pellet, and then to send it into the oesophagus, 

 whose progressive contractions from one end to the other com- 

 plete the operation. But according to the recent experiments of 

 the physiologist just quoted, it would appear that the paunch 

 and the honeycomb by their contraction force the alimentary 

 mass which they contain, between the borders of the furrow of 

 the oesophagus ; and that this, contracting in its turn, takes up a 

 portion of it, separates it, and forms it into the ball which is 

 destined to return along the oesophagus. The paunch is, as we 

 have already said, extremely large ; but it is not always of the 

 same size ; and the differences which are observed in it, show 

 how much the organs of animals may be modified by the circum- 

 stances in which they are placed. In fact, whilst the animals of 

 the Ruminant tribe are young, and are living only on milk, the 

 paunch is smaller than the reed ; and only attains its enormous 

 size when it has to receive grass, a substance that contains but 

 little nourishment, and of which the animal is consequently 

 obliged to eat a considerable quantity. 



100. The intestinal canal, as elsewhere stated (ANIM. PHY- 

 SIOL. 213), presents very considerable differences in its length 

 and diameter, according as the food which has to pass through 

 it has been obtained from the Animal or Vegetable kingdom. 

 Thus, in many of the Carnivora its length is only about three or 

 four times that of the body ; whilst amongst the Herbivora it is 

 usually from ten to twelve times, and sometimes nearly twenty- 

 eight times, this length (in the sheep, for example). In general, 

 it terminates by a direct external aperture ; sometimes, however, 

 it enters a cavity named the cloaca, into which the urinary canals 

 also open. This arrangement is found in the Ornithorhyncus ; 

 and is met with again in the class of Birds ; hence it is an addi- 

 tional point of connection between that curious animal, and the 

 oviparous vertebrata. The salivary glands, the liver, the pan- 

 creas, the peritoneum, and the other appendages of the digestive 



