316 ALWIN M. PAPPENHEIMER 



completely within twenty-four hours, the cell retaining only a 

 faint diffuse greenish tinge. 



If the Janus green be added originally to the plasma in which 

 the tissue is implanted, no growth or emigration of cells occurs. 

 This is probably due to a toxic effect of the stain as well as to 

 an inhibition of amoeboid activity.- 



With new methylene blue GG, in very dilute solutions, there 

 is also produced a very sharp blue staining of the cytoplasmic 

 granules. The nucleus remains unstained, and retraction of the 

 cytoplasmic processes does not occur to any extent. The small 

 thymic cells take a pale diffuse bluish tinge, but the granules 

 though made visible by the altered refractivity, do not them- 

 selves stain. 



Before discussing the origin of these large growing cells, men- 

 tion should be made of their power to phagocyte the small thymic 

 cells. Both in living and fixed preparations, the presence within 

 the large cells of more or less intact small cells is easily recog- 

 nized. Often the nucleus of the ingested small cell stains intensely' 

 with the \'ital stains, such as the new methylene blue, when the 

 majority of the extra-cellular small cells are unstained. It may 

 be fairly assumed from this that the ingested cell is dead. Such 

 staining of the phagocyted cell does not always occur, and the 

 same phagocyte may contain both stained and unstained nuclei 

 of the small cell type. Morphologically, the ingested cell may 

 show no degenerative change save a condensation and increased 

 refractivity of the nuclear material. 



Stainable granulae may be found in considerable numbers in 

 these phagocytic cells, distributed between the ingested small 

 cells, and fat droplets. This observation is not in accord with 

 the statement of Schulemann (26), that cells which have used 

 up their 'receptors' in the process of phagocytosis no longer gi\-e 



- Tlirousli the kindness of Professor Wlierry, who supplied me witli a cullnre, 

 it was possible to try the effect of the dilute solutions of Janus green upnv I lie 

 motility of Amoeba Umax. Amoeboid aetivity was completely inhibited after a 

 few minutes, the amoebae taking on a globular form. A control on the same 

 slide, to which a drop of Ringer's solution was added, remained actively motile 

 after twonty-foui- hours. 



