DIGESTIVE SYSTEM. 257 



Subdivision. — The large intestines, like the small, are three in 

 number, viz. the cotcum, colou^ and rectum: they do not, how- 

 ever, bear the same degree of resemblance, one to another, as the 

 divisions of the small. 



THE CGECUM or blind gut, the first subdivision of the laige 

 intestines, originates in a bulky capacious head or receptacle, 

 called the cacarn caput coli, or blind head of the colon, from 

 which it extends downward, and terminates in a blind extremity 

 or cul-de-sac : from this part, in the human subject, proceeds a 

 slender elongation of gut, about the size of a quill, denominated 

 the appendix vermiformis. Before we proceed further in the 

 description of the coecum, it is proper to notice the manner in 

 which the small are united to the large intestines. The termi- 

 nation of the ileum projects for some way into the caput coli, and 

 does so at right angles both with it and with the coecum, so that 

 the contents, having once passed the ileum, are not likely to 

 return : independently of this preventive contrivance, however, 

 there is a valve at this part very like that at the pylorus. This 

 valve, the valvu/a coli, is formed of a doubling of the internal 

 coat, within which is folded a circular band of muscular 

 fibres; and in its shape resembles a half-moon, so that it is not 

 equally prominent at every part : its office is that of permitting 

 certain alimentary matters and all fluids to pass from the ileum, 

 but to oppose their return. 



Peculiarities. — The coecum differs from all the other guts, in 

 liaving but one opening into it; consequently all matters that 

 have once entered it, must re-ascend into the caput coli in order 

 to continue their route. The exterior parts are braced by three 

 longitudinal bands, and puckered by them into three sets of cells 

 internally ; these cells, which are abundantly supplied with 

 bloodvessels and absorbents, extend the surfaces for absorption 

 and secretion, at the same time that they prolong the stay of 

 the contained matters. The contents of this gut after death are 

 generally found to be fluid : it would appear, indeed, to be the 

 proper receptacle for fluids ; for if we give a horse water to 

 drink, the greater part of it will flow at once through the sto- 

 mach and small guts, and collect within the coecum. 



Capacity. — It will hold about four gallons of fluid. 



THE COLON in the horse is a gut of enormous size, being 

 the most capacious and longest of the large intestines. 



Capacity. — It will contain about tvvelve gallons of water, a 

 greater quantity than the small intestines will hold, put them all 

 together. 



Form and Course. — This is an intestine possessing a pecu- 

 liarity of figure as well as course. It begins at the ccecum caput 

 l1 



