STOMACHS OF RUMINANTS. 143 



When the mass, after being thoroughly ground down by 

 the teeth, is again swallowed, it passes along the oesophagus 

 into the third stomach (3,) the orifice of which is brought 

 forward by the muscular bands, forming the two ridges al- 

 ready noticed, which are continued from the second sto- 

 mach, and which, when they contract, effectually prevent 

 any portion of the food from dropping into either of the pre- 

 ceding cavities. In the ox, this third stomach is described 

 by Sir E. Home, as having the form of a crescent, and as 

 containing twenty-four septa, or broad folds of its inner 

 membrane. These folds are placed parallel to one another, 

 like the leaves of a book, excepting that they are of unequal 

 breadths, and that a narrower fold is placed between each of 

 the broader ones. Fig. 314 represents this plicated struc- 

 ture in the interior of the third stomach of a bullock. What- 

 ever food is introduced into this cavity, which is named, 

 from its foliated structure, the many-plies stomach, must 

 pass between these folds, and describe three-fourths of a cir- 

 cle, before it can arrive at the orifice leading to the fourth 

 stomach, which is so near that of the third, that the distance 

 between them does not exceed three inches. There is, how- 

 ever, a more direct channel of communication between the 

 oesophagus and the fourth stomach (4,) along which milk 

 taken by the calf, and which does not require to be either 

 macerated or ruminated, is conveyed directly from the oeso- 

 phagus to this fourth stomach; for, at that period, the folds 

 of the many-plies stomach are not yet separated, and adhere 

 closely together; and, in these animals, rumination does not 

 take place, till they begin to eat solid food. It is in this 

 fourth stomach, which is called the reed, that the proper di- 

 gestion of the food is performed, and it is here that the coa- 

 gulation of the milk takes place; on which account the coats 

 of this stomach are employed in dairies, under the name of 

 rennet, to obtain curd from milk. 



A regular gradation in the structure of ruminating sto- 

 machs may be traced in the different genera of this family 

 of quadrupeds. In ruminants with horns, as the bullock 



