40 Th. Lewis, 



the trabeciüae (pi. II. fig'. 15), and also other irregular cells, similarly 

 filled, in close connection with reticulum fibres. In one cell, drawn in 

 the figure, and which was more swollen than the remainder, an en- 

 closed erythrocyte was observed, and this large cell was continuous by 

 means of a protoplasmic process with the endothelial lining of a trabe- 

 cular strand. It is also certain that in some glands, where phagocytes 

 are especially numerous, the reticulum seems considerably reduced, 

 though the actual reticulum fibres, which often stain but lightly, are not 

 scarcer, hut rather, the endothelium or "reticulum cells^^ usually at- 

 tached to them are absent. Nothing has been observed suggesting the 

 origin of phagocytes from the endothelium of capillaries but it is pro- 

 bahle that endothelial cells in other situations are capable of deve- 

 loping into cells with blood destroying properties. The question cannot 

 be definitely settled until a really good series of intermediate forms 

 between such an endothelium cell and a phagocyte has been observed. 

 In discussing the origin of the cells under consideration Schumacher 

 has described an appearance to which he gives the name "Zwischen- 

 gewebe". This he found in the sinus, in the neighbourhood of the 

 capsule, consisting of densely packed phagocytes, which were so closely 

 pressed together as to occasionally assume hexagonal outlines ; in these 

 cells he described the process of mitosis as actively proceeding, believ- 

 ing such groups of cells to be the situation in which the phagocytes 

 of the gland, generally, have their origin. Structures somewhat resembling 

 these appearances certainly exist in some of the glands of the rat, but 

 by no means frequently, and I am not convinced that they represent 

 the only or even the chief position in which phagocytes have their 

 origin. 



4. Nature of the pigment found in the glands. 



A general misconception has arisen in regard to the extent to 

 which the breaking down of the blood pigment may proceed in hïemo- 

 lymph glands. It is surprising to find the statement by Halliburton^), 

 that the spleen cells do not proceed so far as to liberate hgemoglobin 

 from the corpuscles. If this change does not occur, what possible 



^) Essentials of Cliemical Physiology. 1899. 



