440 VERA DANCHAKOFF 



to be necrophages in a high degree. Podwissotski and others 

 have described the process of necrophagism in various tumors; 

 hving tumor cells ingest debris of dead tumor cells which inside 

 of the phagocyte have been mistaken for parasites. In the 

 grafts, tumor cells are seen to ingest dead tumor cell material 

 in great quantity. Necrotic tumor cells, of which the structure 

 is still recognizable, as well as cell material which has entirely 

 lost its structure are incorporated into the cytoplasm of tumor 

 cells, fragmented, and finally completely digested. 



It is remarkable that though embryonic mesenchymal cells 

 show a great tendency to surround the extravascular erythro- 

 cytes or dead cell material of their own kind, they seldom show 

 any inclination to ingest dead tumor cells. It is true that they 

 are very small in comparison with the tumor cell, but they 

 show no tendency to surround them even in the form of plas- 

 modial accumulations or giant-cells. Most of the tumor cells 

 on the contrary are generally seen to contain in their cytoplasm 

 acidophilic necrotic masses which gradually disappear. The 

 tumor cells have to be considered, therefore, as having a posi- 

 tive chemotropism toward their own dead cell material, and to 

 possess an intracellular digestive power over it. 



It is interesting to observe the effect of a great quantity of 

 ingested necrotic cell material on tumor cells undergoing mitosis. 

 The mitotic figure may become greatly distorted by the accumu- 

 lation of the ingested material, and the chromosomes grouped in 

 a very irregular manner. Other interesting consequences may 

 be observed in the division process of a cell with ingested material. 

 If the latter chiefly occupies one pole of the cell, the division 

 process in the cell proceeds as in a meroblastic egg; a complete 

 division fails to take place, though a deep furrow passing through 

 the active cytoplasm indicates the respective boundaries of the two 

 cells. Both of the cells may simultaneously undergo a further 

 mitosis. The presence of large ingested masses may lead in this 

 manner to the production of multipolar mitoses sometimes more 

 or less regular, at other times remarkable for their irregularity. 



Dead tumor cells in various stages of disintegration are not 

 the only material which the tumor cells are capable of ingesting. 



