212 



THE INTESTINES. 



ileum. Along the outside of tlie caecum run three strong bands, 

 each of them shorter than that mtestiiie, and thus puckering it 



Fig. 30. 



up, and ibrming it into three 

 sets of cells, as shown m the 

 accompanying side cut. 



That portion of the food 

 which has not been taken up 

 by the lacteals or alsorbent 

 vessels of the small intestines, 

 passes through this valvulai 

 opening of the ileum, and a 

 part of it enters the colon, 

 while the remainder flows 

 into the caecum. Then, from 

 this being a blind pouch, and 

 from the cellular structure of 

 this pouch, the food must be 

 detained in it a very long time ; and in order that, during this 

 detention, all the nutriment maybe extracted, the caecum and its 

 cells are largely supphed with blood-vessels and absorbents. It is 

 principally the fluid part ol" the food that seems to enter the caecum. 

 A horse will drink at one time a great deal more than his stomach 

 will contain ; or even if he drinks a less quantity, it remains not 

 m the stomach or small intestines, but passes on to the CEecum, 

 and there is retained, as in a reservoir, to supply the wants 

 of the system. The caecum will hold four gallons. 



The colo7i is an intestine of exceedingly large dimensions, and 

 is capable of containing no less than twelve gallons of liquid or 

 pulpy food. It has likewise, in the greater part of its course, 

 three bands like the caecum, which also divide it, internally, into 

 the same description of cells. The intention of this is evident, — 

 to retard the progress of the food, and to give a more extensive 

 surface on which the vessels of the lacteals may open ; and 

 therefore, in the colon, all the chyle is finally separated and 

 taken up. The food does not require to be much longer detained, 

 and the mechafiism for detaining it is gradually disappearing. 

 The colon, also, once more contracts in size, and the chyle hav- 

 ing been all absorbed, the remaining mass, being of a harder 

 consistence, is moulded into pellets or balls in its passage through 

 these shallower cells. 



At the termination of the colon, the rectntn (straight gut) 

 commences. It is smaller in circumference and capacity than 

 the colon, although it will contain at least three gallons of water. 

 It serves as a reservoir for the dung until it is evacuated The 

 faeces descend to the rectum, which somewhat enlarges to receive 

 tJiem ; and when they have accumulated to a certain extent the 



