THE FKKIT<)NF.rM. 305 



The various folds and mesenteries carry the blood-vessels and 

 nerves to the different organs ; in this course the vessels are sur- 

 rounded by large lymphatics, which communicate with each other. 



B- 



2J 



Preparations from the peritoneum of Rutna etcuknta. G. H. 



I. From peritoneum of the ventral wall of abdomen, stained with silver and logwood {Hartnack, 



Oc. I, Syst. 7). 

 II. From mesentery of small intestine of Rana tucultnta, stained with silver (Hartnack. Oc. I. 



- 7)- 



III. Preparation to show ciliated cells between non-ciliated cells ; after Neumann. 



IV. Vertical section at border of liver to show ciliated epithelium ; after Neumann. 



A Stoma. 

 B Pigment-cells. 

 : Hated cells. 

 D Non-ciliated cells 



b. Minute structure (Fig. 201). 



[The peritoneum is a serous membrane, formed for the most part 

 of a layer of irregular endothelial cells, arranged on a thin layer of 

 subserous, connective-tissue (Fig. 201 I, II, and III). 



The endothelial cells are attached to each other by cement-sub- 

 stance, easily stained by silver nitrate. The cells covering the 

 general surface of the peritoneal cavity are larger and broader than 

 those covering the mesentery of the small intestine (compare I and 

 II, Fig. 201). 



At various points stomata are found, bordered by smaller and 

 more deeply staining epithelium (I, A). The membrane covering 

 the general cavity is also much more pigmented than that covering 

 the mesentery (compare I and II). 



Various portions of the peritoneal surface possess ciliated cells, 



