ALIMENTARY CANAL. 211 



the elevation of the mucous membrane to form folds, villi, and 

 papillae. 



A diagram of the human intestinal tract and its appendages 

 is given in Fig. 172. All the appendages of the canal arise in the 



Gls 



FIG. 172. DIAGRAM OF THE ENTIRE ALIMENTARY TRACT or MAN. 



Gls, salivary glands ; PA, pharynx ; Gl.th, thyroid gland ; Gl.thy, thymus gland ; 

 Lg, Inng ; Oe, oesophagus ; "Z, diaphragm ; Mg, stomach ; Lb, liver ; Pa, pancreas ; 

 Dd, small intestine ; Vic, ileo-colic valve ; Pr, vermiform process of caecum ; 

 Ca, ascending colon ; Ct, transverse colon ; Cd, descending colon ; , rectum ; 

 A, anus. 



embryo as outgrowths from the hypoblast, and are thus of epithelial 

 origin : they either remain throughout life as glandular organs, or at 



p 2 



