510 



PHYSIOLOGY 



CHAP. 



arborisations with anastomosing trunks, the extreme branches of 

 which form parallel canaliculi, corresponding to intertendinous 

 clefts (Fig. 244). 



The black lines of intercellular impregnation are clearer and 

 more delicate on the peritoneal face where there are large polygonal 

 cells, with here and there small islands of lesser and rounded cells ; 

 these are the lymph cells which invest the orifice and walls of the 

 small canals that bring the peritoneal cavity into direct communi- 

 cation with the lymphatic rete of the tendinous centre (Fig. 245). 





FIG. 243. Rabbit's diaphragm, viewed from abdominal surface, with lymphatic rete injected with 

 Prussian blue. (C. Ludwig and Sclnveigger-Seydel.) The figure is somewhat reduced. 



According to Ranvier there is no need to invoke the existence of 

 intercellular stomata to explain the ready penetration of coloured 

 fluids or solid particles from the peritoneal cavity to the lymphatic 

 plexus, since the small cells which occupy the orifices of the afore- 

 said canaliculi do not completely occlude them. Still the retro- 

 peritoneal membrane of the frog, which forms the wall of the 

 cisterna lyniphatica major in these animals, has, according to 

 Schweigger-Seydel and Dogiel and Ranvier himself, true stomata 

 or apertures surrounded by epithelial cells which are somewhat 

 differentiated and communicate freely with the peritoneal cavity 

 (Fig. 246). 



