310 



THE ANATOMY OF THE HORSE. 



buted over the wall, but are collected into distinct bands, the areas 

 between the bands being provided only with circular fibres. When these 

 bands contract, they shorten the intestine, and throw the wall of the 

 bowel between them into alternate ridges and fuiTows. The number of 

 these bands is difierent at different points. The caecum has four. The 

 colon in its 1st part has also four. Three of these disappear on the 

 2nd part, so that at the pelvic flexure there is only a single band, on 

 the concave side of the flexure. This single band is continued along 

 the 3rd part, and near the diaphragmatic flexure other two bands 

 originate. The 4th part has three bands. The single colon has two 

 bands, one on each curvature, and these are continued on the first half 

 of the rectum, but are lost on its terminal half, as will be seen in the 

 dissection of the pelvis. The inner layer of circular fibres is iniiformly 

 distributed. 



3. The Submiicous Coat is a layer of loose areolar tissue uniting the 

 muscular and mucous coats. 



4. The Mucous Coat lines the cavity of the bowel. Its surface is 

 covered by a single layer of columnar epithelium, and in its deeper part 

 it contains^ solitary glands and glands of Lieherkiihn, similar to those of 



Fig. 37. 



Diagrammatic View (magnified) of a small Portion of the Mucor.s :Me.\ 

 Colon (Allen Thomson). 



sane of the 



A small iiortion of the mucous membrane cut perpendicularly at the edges is shown in perspective ; 

 on the surface are seen the orifices of the crypts of Lieberkiihn or tubular glands, the most of them 

 lined by their columnar ei)ithelium, a few divested of it and thus appearing larger ; along the sides 

 the tubular glands are seen more or less equally divided by the section ; these are resting on a wider 

 portion of the submucous tissue, from which the blood-vessels are represented as passing into the 

 Bpaces between the glands. 



the small intestine. No Peyer's patches are found in it; and it is with- 

 out villi. The foldings of the wall of the bowel produced by the longi- 

 tudinal muscular bands involve all the coats, and the interior therefore 

 shows the alteniately ridged and furrowed appearance already seen on 

 the exterior. 



