G8 ANATOMY OF THE LYMPHATIC SYSTEM. 



one side like a fold, we may convince ourselves, searching at the 

 edge of this cord, that the germinating polyhedral, or even conical 

 cells of the surface, are to be referred almost as abundantly to the 

 pseudo-stomata as to the endothelium of the general surface. At 

 least, I have often met with appearances, not only in these cords, but 

 also on the small knots, where, in a given profile view, whether 

 optical-profile or section-profile, a young endothelium cell of the 

 surface alternated with an endothelial-like bud of a pseudo-stoma. 

 This distinction in an optical-profile view, such as on a fold, is some- 

 times combined with great difficulties. I myself considered all these 

 young endothelial cells of the surface for a long time simply as the 

 surface endothelium, until, by the frequency of pseudo-stomata on the 

 lymphatic knots of the rabbit's omentum, and by the discovery that 

 numerous young cells of the surface, quite resembling endothelial 

 eells, stand in direct connection with the pseudo-stomata, I became 

 aware of the inaccuracy of that view. I submitted, therefore, the 

 young endothelium of the surface of these knots and cords to a subse- 

 quent exact examination. I have accordingly studied this relation 

 especially, first upon sections through the large knots and cords of the 

 pleura of the cat, through the knots and cords of the tuberculous 

 omentum of the guinea-pig, and have so discovered that, in the first 

 place, the distribution of pseudo-stomata upon these lymphatic knots 

 is a very extensive one, by far more extensive than I was at first 

 inclined to accept, and secondly, that a great number of the young 

 endothelial-looking cells are in continuity with the pseudo-stomata, 

 that is, with the protoplasmic processes which usually represent the 

 pseudo-stoma. Once acquainted with the fact itself, I came speedily 

 into a position to confirm, under all conditions, the fact previously 

 mentioned, that the proliferation affects not only the endothelium 

 which surrounds a pseudo-stoma, but that the pseudo-stoma itself 

 takes part in it. It is clear that there is no necessity to make a 

 distinction between those young cells which originate from the super- 

 ficial endothelium surrounding a pseudo-stoma, and those of the 

 latter themselves, since there exists no morphological difference ; 

 they are quite alike in their appearance, nucleus, form, and size ; 



