30 ELEMENTS OF HISTOLOGY. [Chap. iv. 



the peritoneum is called the septum cisternae lym- 

 phaticae magnse, and on it occur numerous holes or 

 stomata, by which a free communication is established 

 between the two cavities. On the peritoneal surface 

 of this septum the stomata are often bordered by 

 germinating cells. In the female frog, these and 

 other germinating endothelial cells of the peritoneum 

 (mesogastrium, mesenterium, septum cisternae) are 

 ciliated. 



34. The omentum and parts of the pleura are, in 

 the adult human subject, ape, dog, cat, guinea-pig, rat, 

 &c., of the nature of a fenestrated membra^ie (Fig 21), 

 bands of fibrous tissue of various sizes dividing and 

 reuniting, and leaving between them larger or smaller 

 holes, in shape oblong or circular. These holes 

 or fenestrse are not covered with anything, the endo- 

 thelial cells adhering only to the surfaces of the 

 bands without bridging over the fenestrse. On the 

 peritoneal surface of the diaphragm the endothelial 

 cells possess a different arrangement from that on 

 the pleural side ; on the former surface a number of 

 lymph channels (that is, clefts between the bundles 

 of tendon and muscle) radiate towards the middle 

 of the central tendon. The endothelium of the free 

 surface over these lymph channels is composed of 

 much smaller cells than at the places between, 

 so that the endothelium of the peritoneal surface of 

 the diaphragm shows numbers of radiating streaks 

 of small endothelial cells. Many of these. small cells 

 are not flattened, but polyhedral, and of the nature 

 of germinating cells (Fig. 20.) The above-mentioned 

 stomata occur amongst these small endothelial cells. 



