Chap. XI.] 



THE LYMPHATIC VESSELS. 



8 9 



cysts lined with ciliated endothelium are sometimes 

 found. Behind the peritoneal cavity of the frog, 

 along and on each side of the vertebral column, exists 

 a similar large lymph sinus, called the cisterna lympha- 

 tica magna. 



116. In all instances these cavities are in direct 

 communication with 



the lymphatics of the 

 surrounding parts by 

 holes or open mouths 

 (stomata), oiten lined 

 by a special layer of 

 polyhedral endothe- 

 lial cells germinat- 

 ing cells (Figs. 54, 

 55). Such stomata 

 are numerous on the 

 peritoneal surface of 

 the central tendon of 

 the diaphragm, in 

 which are found 

 straight lymph chan- 

 nels between the 

 tendon bundles, and these channels communicate here 

 and there with the free surface by stomata. A 

 similar arrangement exists on the costal pleura, the 

 omentum, and the cistern a lymphatica magna of the 

 frog. (See Chapter IV.) 



117. The erous membranes consist of a 

 matrix of fibrous connective tissue with networks of 

 tine elastic fibres; they contain networks of blood 

 capillaries and numerous lymphatic vessels arranged in 

 (superficial and deep) plexuses. Those of the pleura 

 costalis or rather, intercostalis and of the diaphragm 

 and pleura pulmonalis, are most numerous. They are 

 important in the process of absorption from the pleural 

 and peritoneal cavity respectively. Lymph and lymph 



Fig. 55. Endothelium and Stomata of 

 the Peritoneal Surface of the Septum 

 Cistern Lymphatic Magnae of the 

 Frog. (Handbook.) 



