23-2 OUTLINES OF EQUINE ANATOMY. 



tary class. The internal or circular, wliicli run round the 

 intestinal tube, are found in all parts evenly diffused over 

 the surface of the intestine, being anteriorly in direct con- 

 nection with the circular fibres of the stomach at the 

 pylorus. Posteriorly collected into a mass, which forms 

 the internal portion of the sphincter ani. The external w 

 loncjitucli7ial order of fih'es is evenly diffused over the surface 

 of the small intestine and of the rectum, while in the csecum 

 and colon these fibres are collected into thick bands, which 

 run longitudinally to the course of the bowel, and are more 

 or less numerous in different parts. Being shorter than 

 the bowel itself, and at the same time intimately attached 

 to its walls, they serve to " pucker" up its surface into a 

 number of cavities, which give it a peculiar appearance, 

 whilst by division of the bands it may be reduced to a tube 

 of uniform diameter and of much greater length. On ex- 

 posing the bowels of an animal shortly after death we may 

 observe the vermic2ilar or ^yeristaltic action of the intestines, 

 that slow consecutive contraction of their fibres commencing 

 anteriorly and extending backwards, whereby the ingesta 

 is slowly propelled from the pylorus to the anus. The 

 mucous coat of the bowels is of a reddish-grey colour and 

 slimy nature, extends from the pylorus (where it is con- 

 tinuous with the villous portion of the gastric mucous 

 membrane) to the anus, where it gradually blends with the 

 common integument. It consists of corium and basement 

 membrane, on the free surface of which is columnar epi- 

 thelium, and throughout presents depressions of this 

 mucous membrane termed follicles of Lieberhnhn, which 

 secrete mucus, and prominences of the same, villi orpapillce, 

 from the centre of which a lacteal commences, either by a 

 plexus, loop, or a blind pouch, for these are the portions of 

 the intestine from which the lacteals arise, and, though 

 most numerous in the small intestine, they may be found 

 also in the large. Throughout the intestinal tract also we 

 find embedded in the mucous membrane small bodies 

 called solitary gkmds, which consist apparently of a number 

 of cells bound together by somewhat dense areolar tissue, 

 and having blood-vessels runniog through them. They 

 present no ducts, and hence are considered to be analogous 

 in nature and function with the Malpighian corpuscles of 

 the spleen, though some aiithorities assert that by bursting 

 they discharge their contents into the intestine, and thus 



