Nov., 1907.] 



Eleinenfs of An/ Dial PJivsiology. 



687 



of the alimentary canal varies with each species of animal. 

 for instance that the ratio 



Cat. 



We find 



Sheep 

 Ox. and 

 Goat. 



16 



26 



length of alimentaiy canal i 



equals apprdxiniately — 



length of animal + 



GENERAL AXATOMY. — In the course of the alimentary tube we 

 find .some dilatations and constrictions, which mark it off into special 

 parts and to which distinctive names have been given. At the beginning 

 of the canal we find the mouth ; this opens into a short and muscular 

 part common to the digestive and respiratory systems, called the pharynx; 

 then comes a straight narrow portion called the gullet or cesophagus. 

 The lower part of the oesophagus is in some animals dilated forming 

 an organ which is ternvM the crop or proventriculus. This opens into 

 the true stom.\ch which consists of two parts, the fundus and the 



PYLORUS. 



At this point the alimentary canal becomes a thin and very convoluted 

 tube called the small intestine : the first part of the small intestine which 

 always forms a \er\ distinct loop is called the duodenum. The small 

 intestine opens into a dilated pouch called the C^CUM which in some 

 animals takes the form of a long blind tube. The next part of the 

 alimentary canal commencing Pt the caecum is the large intestine or 

 colon ; this merges into the rectum which ends in the anus. 



rm 



Fig. 43. Diaj,n-;ini of Section of Alimentary Tube. — L, cavity of gut; glm., 

 glands of mucous membrane; ep., epithelium; gls., glands in sub-mucous coat; 

 mm., muscularis mucosae; sm., submucous coat; rm., circular muscular coat; Im., 

 longitudinal muscular coat; s., serous or jieritoneal coat; ss., mesentery; gmy. and 

 gsm., nerve ganglia. ^After Sobotta.) 



GENERAL HISTOLOGY.— The wall of the alimentary tube consists 

 of several lavers. Most central is the lining mucous membrane which 

 extends from lips to anus. The character of this mucous membrane 



