THE LYMPHATIC VESSELS OF THE SEROUS MEMBRANES. 53 



of the mesentery, in a very active state of germination, the animals 

 suffering from chronic peritonitis. 



A second kind of stoma verum represents a simple discontinuity 

 of the endothelium of the surface. They lead into a simple lym- 

 phatic lacuna, situated superficially beneath the endothelium, and, as 

 we have seen, lined only on one surface, the lower surface, with an 

 endothelium. The endothelium of the surface which borders such a 

 stoma has very often also a germinating character. This kind of 

 stoma verum is to be found in the omentum of rabbits and the 

 mesentery of frogs and toads. They are also very much easier to 

 demonstrate when these membranes are affected with slight chronic 

 inflammation. 



We have already mentioned, at the beginning of this Essay, that 

 there exist superficial branched cells in the serous membranes which 

 lie either totally or partially between the endothelium of the surface, 

 or, as is more commonly the case, only reach the surface by a process 

 which projects between the superficial endothelium. In the peri- 

 lymphangial nodules and cords described as occurring in the omen- 

 tum and pleura this is the case in an extraordinary degree. We 

 find here a large number of such perpendicular processes, projecting 

 freely between the endothelium of the surface, which proceed from 

 the superficial cells of the cell-network of the matrix of these lym- 

 phatic structures. This may be seen both in the young' and old 

 structures, in true or optical sections, as well as in surface prepara- 

 tions. As we have stated that the branched cells which constitute 

 the matrix of these peri-lymphangial nodules, as well as those of the 

 ground-tissue of any given part, lie in the lymph-canalicular system, 1 

 it is a necessary conclusion that the lymph-canalicular system opens 



1 We must again repeat here that by this we only mean the negative picture whose 

 position is formed by the branched lymph-canalicular cells themselves, with their pro- 

 cesses. We are therefore not in precise agreement with the views of Lavdovsky and 

 Afonassiew. These authors consider that in the serous membranes a superficial lymph- 

 canalicular system exists as such, i.e. without the lymph-canalicular cells ; and that this 

 quasi empty lymph-canalicular system opens freely on the surface by a number of fine 

 perpendicular canals. We, on the contrary, consider that the branched lymph-canalicular 

 cells reach the surface through processes ; and as we deny the existence of a lymph-canal- 

 icular .system without cells, and rather consider it only as a negative picture of the latter, 

 the statement, that the lymph-canalicular system opens freely on the surface by canals, is 



