238 



COMPARATIVE ANATOMY. 



pared with tin- epithelial cells, E 1 JP-, of the intestine of a lower 

 Vertebrate, in Fig. 194, A, where they are shown putting out 



B M M 



G- - 





Fie. 104.- A, SKMIDIAGKAMMATIC TRANSVERSE SECTION OF A PORTION OF THE 

 WALL OF THE INTESTINE. (Combined from the condition seen in both lower 

 and higher Vertebrates.) 



The connective-tissue layer and epithelium are designedly drawn much too Lug.' 

 as compared with the outer coats. To the left of the figure would be the 

 body-cavity ; to the right, the alimentary cavity. 



P, peritoneal investment of the gut ; M, longitudinal muscular layer ; M 1 , circular 

 muscular layer; Z, connective-tissue layer; S, mucous membrane, which is 

 raised to form villi at Zo ; G, G, vessels, the larger trunks running between the 

 peritoneum and the muscular layer : the finer vessels branch out into the inter- 

 mediate layer ; these surround the masses of lymph-cells, LL, as well as the 

 glands, mi. I send fine loops into the villi (at G 1 ) ; DD, apertures of the glands ; 

 K, /', epithelial cells of the mucous membrane, with their striated border, from 

 which at E l amceboid processes are extruded: in Fig. B, a, b, these cells are 

 drawn to a much larger scale (.SVr, striated bonier) ; Ly, scattered lymph-cells 

 in (be intermediate layer; L l , L'\ lymph-cells in the act of passing through 

 the nine., us membrane ; at L", several have already passed into the alimentary 

 cavity, mid are beginning to ingest the contained nutritive particles by means 

 of their amn l",id processes ; LL, masses of lymph-cells (solitary follicles) ; 

 Lym, lymph -vessels in the villi. 



:nnu -Ixtid processes, and in Fig. 104, B, where the cells a, 1), are 

 slio\\n di-.'iwii to ;i l.-irger scale. Besides these absorptive epithelial 



