THE LYMPHATIC VESSELS OF THE SEROUS MEMBRANES. 51 



tribution of the first kind of stomata vera, the following is to be 

 noticed : 



In great numbers they are to be met with on the peritoneal sur- 

 face of the centrum tendineum. We have had the opportunity to 

 mention that the straight lymphatic capillaries, the deep ones as well 

 as the superficial ones, stand in free communication with the peri- 

 toneal cavity by means of vertical lymphatic channels. The free mouths 

 of these are the stomata in question. These vertical lymphatic 

 channels are generally situated in chains behind each other ; they 

 are more numerous and shorter for the superficial straight lymphatics 

 than for the deep ones. The vertical lymphatic channels of the latter 

 exhibit in some rare cases a peculiarity, which consists in this : if from 

 the deep, straight lymphatic capillary a vertical lymphatic channel 

 is given off just at the point where the former is covered by a super- 

 ficial lymph-capillary, then we see that the vertical lymphatic channel 

 passes simply through the superficial straight vessel, that is to say, 

 the vertical lymphatic channel appears to be invaginated in the 

 straight lymphatic vessel. 



In the vertical channels of the deep straight lymphatic capillaries, 

 having a considerable length, it is very easy to recognise that they are 

 lined by a special layer of endothelium, which in the most cases, 

 exactly like that of the corresponding stoma, consists of polyhedral 

 germinating elements. The layer of endothelium which lines the 

 vertical channel is also distinguishable in those of the superficial 

 straight vessels if they are not collapsed. Adjusting from the peri- 

 toneal surface, one sees first the germinating endothelium of the stoma, 

 then a similar layer of polyhedral endothelial elements surrounding 

 the vertical channel like a corona. 



Over the above-mentioned excavations and sinuses of the lym- 

 phatic capillaries of the peritoneal serosa of the centrum tendineum 

 there exist also stomata vera, i.e. vertical lymphatic channels which, 

 like those of the superficial straight capillaries, are only of a very 

 limited length. The endothelium does not differ in any respect from 

 that of the latter. Quite as numerous are the stomata vera, viz. 

 the vertical lymphatic canals in the omentum and pleura ; we find 

 them on the lymphatic capillaries and lymph-sinuses in the omen- 



K 2 



