MUCOUS COAT. 389 



fibres are so pale and the layers are so thin that their pres- 

 ence is demonstrated with great difficulty. In the rectum 

 they are somewhat more numerous. About an inch above 

 the anus the circular fibres are collected into a pretty well- 

 marked muscular ring, which has been called the internal 

 sphincter. 



Mucous Goat. The mucous lining of the large intestine 

 presents several important points of difference from that which 

 is found in the small intestine. It is paler, somewhat thick- 

 er, firmer, and more closely adherent to the subjacent parts. 

 In no part of this membrane are there any folds, like those 

 which form the valvulse conniventes of the small intestine ; 

 and the surface is perfectly smooth and free from villosities. 



Throughout the entire membrane, from the ileo-csecal 

 valve to the anus, are innumerable orifices which lead to 

 simple follicular glands. These structures resemble in all 

 respects the follicles of the small intestine, except that they 

 are a little longer, owing to the greater thickness of the mem- 

 brane, and are wider, and rather more numerous. Among 

 these small follicular openings are found, scattered irregularly 

 throughout the membrane, larger openings which lead to 

 utricular glands, resembling the closed follicles, in general 

 structure, except that they have an orifice opening into the 

 cavity of the intestine, which is sometimes so large as to be 

 visible to the naked eye. 1 The number of these glands is very 

 variable, and they are irregularly disseminated throughout the 

 intestine in company with the closed follicles, except in the 

 rectum, where they are absent. In the caecum and colon, a 

 number of isolated closed follicles are generally found, which 

 are identical in structure with the solitary glands of the small 

 intestine. These are exceedingly variable, both in number 

 and size. 



The mucous membrane of the rectum, in the upper 

 three-fourths of its extent, does not differ materially from that 



1 SAPPEY, op. c^.,tome iii., p. 192. 



