184 ACT OF RUMINATION. 



here that we find the curious arrangement of water-cells in the 

 stomach of the Camel, by which that animal is enabled to 

 retain a supply of water for several days. These cells corre- 

 spond with the little pits which are seen in the honey-comb 

 stomach of the Sheep, but are much deeper, and their orifices 

 may be closed by the action of a set of muscular fibres which 

 pass in every direction round each, so as to form a net-work 

 including these orifices in its meshes. 



199. After the food has been macerated in the fluids of the 

 first and second stomachs, it is returned to the mouth by 

 a reversed peristaltic action of the oesophagus, which brings 

 it up as a succession of globular pellets, that are formed by 

 compression in a sort of mould at the lower end of the oeso- 

 phagus. These pellets are subjected within the mouth to 

 mastication and insalivation ; and the food is then ready for 

 the real process of digestion. It is this mastication which is 

 commonly known as the " chewing of the cud ; " and the 

 animal, whilst performing it, seems the very picture of placid 

 enjoyment. When again swallowed, the food is directed, by 

 a peculiar valvular groove at the bottom of the cesophagus, 

 into the third stomach, commonly termed the manyplies, 

 from the peculiar manner in which its lining membrane is 

 arranged. This presents a number of folds, lying nearly close 

 to one another, like the leaves of a book, but all directed, by 

 their free edges, towards the centre of the tube, a narrow 

 fold intervening between each pair of broad ones. The food 

 has, therefore, to pass over a large surface, before it can reach 

 the outlet of the cavity ; and this leads to the fourth stomach, 

 commonly termed the reed. This is the seat of the true digestive 

 process, the gastric juice ( 204) being formed here only ; 

 and it is from this that the rennet is taken, which is used 

 in making cheese to cause the milk to coagulate or curdle. 

 In the sucking animal, the milk passes directly into this 

 fourth stomach, without entering either the first or second 

 stomachs, and without being delayed in the third, the folds 

 of which adhere together so as to form a narrow undivided 

 tube. The paunch is at that time comparatively small, being 

 of less size than the reed; and its dimensions increase, as 

 soon as the young animal begins to distend it by swallowing 

 solid vegetable matter. 



200 In the digestive apparatus of Birds, we find a con- 



