ALIMENTAEY CANAL 319 



is about four inches long, and its walls resemble 

 Peyer's patches in appearance and structure. 



In the rabbit the c»cum is of enormous size, as 

 in most herbivorous mammals with simple stomachs. 

 7. The colon is about a foot and a half in length. The 

 first part of it is very markedly sacculated, the 

 sacculations lying in three longitudinal rows, 

 separated by smooth areas of unequal width. 

 Towards the rectum the walls become smooth. 

 The rectum or terminal portion of the intestine is a 

 narrow tube, about two and a half feet in length, 

 pale in colour, and presenting a moniliform appear- 

 ance, owing to the contained faecal pellets. At its 

 hinder end it passes through the pelvic cavity to 

 terminate at the anus. 



B. Internal Structure of the Alimentary Canal, 

 The stomach. 



Bemove the stomach from the body, cutting across the 

 oesophagus and duodenum close to it, and talcing care not to 

 injure the vessels of the liver. Slit up the stomach along its 

 posterior surface : wash, and examine it under water. 



The wall of the stomach consists of an outer 

 peritoneal investment ; a middle muscular layer, 

 thickened at the pyloric end ; and an inner layer of 

 mucous membrane, which is raised into irregular 

 longitudinal folds. The pyloric orifice is narrowed 

 by a prominent muscular rim. 



2. The small intestine. 



Cut out a small piece from the wall, and examine its inner 

 surface under water. 



The villi are minute tag-like processes of the 

 mucous membrane, covering its surface, and giving 

 it a velvety appearance. 



Peyer's patches present a honeycombed appear- 

 ance, the depressions being occupied by smooth 

 convex lymph-follicles, bordered by villi. 



