THE HOESE. 



105 



The first, or the peritoneal, has nothing 

 peculiar, beyond its enclosing a little trian- 

 gular space all along the upper attached 

 border of the gut. The looseness of the 

 peritoneal folds attaching the small intes- 

 tine is very marked; and Colin (Soc. cit.) 

 notes, that the mesentery is proportionately 

 larger in young than in adult quadrupeds, 

 so that the gradual shortening of this ex- 

 plains the spontaneous reduction of exom- 

 phalus or umbiKcal hernia. 



The second, or muscular coat, is mostly 

 developed at the commencement of the 

 duodenum and terminating portion of the 

 ileum. It consists of white involuntary 

 fibres, arranged so as to form an outer 

 longitudinal layer, and an inner cu'cular one, 

 both of which completely encircle the gut. 



The third, or cellular coat, is similar to 

 that of the stomach, in being disposed in 

 two layers, so as to connect the three coats 

 together. It is especially condensed on the 

 inner surface of the muscular coat, so as to 

 take the appearance of a fibrous tunic, at- 

 tached to the mucus lining by loose cel- 

 lular tissue. 



The fourth, or mucus, coat is thin, hav- 

 ing a velvet appearance, due to villi, pecu- 

 liarly smaU in the intestines of the horse, 

 but remarkably developed in other animals, 

 especially carnivora and fishes. The villi 

 may be seen by a pocket lens, on a well- 

 washed piece of intestinal mucus mem- 

 brane, and between them are seen numer- 

 ous foramina, which are the openings of 

 tubular glands, known as the crypts of Lie- 

 berkuehn. 



In addition to the tubular glands, by dis- 

 secting, from without, the muscular from 

 the mucus coat, lining the commencement 

 of the duodenum, we find clusters of vesi- 

 cles, similar to the vesicular structure of the 

 salivary and pancreatic glands. These 

 form distinct layers, provided with ducts, 

 which open on the free surface of the mem- 

 brane ; and Dr. Todd states that Brunner's 

 glands, or, as he calls them, the duodenal, 

 are more developed in the horse than in any 

 other animal he has hitherto examined them 



in. 



We have next to treat of the solitary 

 glands — glandulae solitarias — peculiar and 

 rather scanty bodies, visible at various parts 

 of the small intestine. These are vesicu- 

 lar, and without any opening when in the 

 perfect state, surrounded- by villous pro- 

 cesses and Lieberkuehnian follicles. Some 

 of the villi also project from the surface of 

 the so-called glands, which are most ap- 

 parent when distended with secretion. 



About the second half of the jejunum, 

 and along the whole of the ileum, we see 

 longitudinal patches, varying from half an 

 inch to even three inches in length, scat- 

 tered all over, but more especially situated 

 near the superior or attached border of the 

 small intestine, which is contrary to the 

 faulty description of some recent authors. 

 These patches, distinguished as Peyer's 

 glands or patches, also as Agminated glands 

 — GladdulaB agminatse seu aggregatae — con- 

 sist of an accumulation of small bodies, each 

 resembling a glandula solitaria in miniature, 

 being also destitute of a natural aperture. 

 Colin (loc. cit.) states that they are first 

 seen at a distance of about six feet and a 

 half from the pylorus, and the least num- 

 ber of them he has ever counted has been 

 102, whilst the utmost has been 158. 



The mucus membrane of the small in- 

 testine is thrown into folds, at different 

 parts, which are transverse, and scalloped 

 near the pylorus, whilst in other parts they 

 are mostly longitudinal ; these are all tem- 

 porary folds. There is no such arrange- 

 ment as the valulas conniventes in the small 

 intestines of the horse, though recent wri- 

 ters of great eminence have described them. 

 About five inches from the pylorus, at 

 the superior border of the duodenum, is a 

 semicircular fold, which, if elevated, ad- 

 mits of the finger being thrust behind it 

 into the wide biliary duct. The opening 

 of the pancreatic duct is also visible beneath 

 this fold, but it is not so capacious as the 

 one last mentioned. 



LARGE INTESTINE. 



The large intestine constitutes the termi- 

 nating portion of the alimentary canal, 



14 



