50 ANATOMY OF THE LYMPHATIC SYSTEM. 



as far as I can see, only by Dybkovski for the pleura costalis. 

 Dybkorski has shown on that membrane, after having injected the 

 lymphatics, that the superficial lymphatic vessels lead freely between 

 the endothelium of the surface by short vertical branches. Close to 

 that comes the assertion of Dogiel and Schweigger-Seidel, that the 

 septum cysternse lymph, magnse in frog is perforated by a number 

 of canals stomata that is to say, that the cysterna lymph, magna is 

 in free communication with the peritoneal cavity. According to 

 these observers, large flat endothelial cells on both surfaces of the 

 septum have a radiating arrangement round those stomata; the 

 nucleus of these radiating endothelial cells lies peripherally in that 

 portion with which the cells border the stoma, so that each nucleus 

 causes a roundish projection of the cell into the stoma. We shall see 

 hereafter that these assertions do not correspond perfectly to the facts. 

 Finally, Ludwig and Schweigger-Seidel have drawn attention to 

 the important fact that the peritoneum of the centrum tendineum has 

 a fenestrated arrangement in those parts which cover the straight 

 lymphatics. This fact, together with the experience of Reckling- 

 hausen, brought many authors to the assumption that those small 

 irregularly distributed figures amongst the endothelium above the 

 straight lymphatic channels in silver preparations represent stomata. 

 We come now to deal with the results of our own researches. 

 We distinguish two kinds of stomata on the surface of the serous 

 membranes, namely, stomata vera and stomata spuria or pseudo-sto- 

 mata. The stomata vera are again of two kinds : a. They represent 

 the mouth of a vertical lymphatic channel, which is lined by a special 

 layer of endothelium, and which channel leads into the lumen of a 

 superficial lymphatic vessel ; 6. They represent a discontinuity between 

 the endothelium of the surface, leading into. a simple lymphatic sinus 

 near the surface, which, as we have seen, represents a cavity lined 

 only on one side with an endothelium. Both kinds of stomata vera 

 are bordered by endothelial elements of a more or less distinct ger- 

 minating character, namely, the cells are smaller, polyhedral, dis- 

 tinctly granular, they stain more readily in silver solution, and possess 

 a single, or a constricted, or a divided nucleus. As regards the dis- 



