DIGESTIVE ACTIVITY OF MESENCHYME 465 



No tropism whatever has been observed between the EhrHch 

 sarcoma cell and the allantoic mesenchymal cell. The tumor 

 cell had not undergone any effect due to the mixing with dead 

 adult splenic tissue, as would have been the case if the changes 

 of the tumor cells in a tumor-adult spleen graft were primarily 

 dependent upon the action of some extracellular substance present 

 in the spleen. 



Mesenchjmial cells may, however, not be identical every- 

 where, and may present regional differences in their functional 

 capacities. Splenic mesenchymal cells might be different from 

 allantoic mesenchymal cells, and tumor cells treated by necrotic 

 adult splenic tissue might become accessible for an embryonic 

 splenic cell and not for a mesenchymal cell of the allantois. 



Another series of experiments was made in which tumor was 

 grafted in a mixture of necrotic adult splenic tissue and em- 

 bryonic spleen. It was expected that if the necrotic adult 

 splenic tissue contained extracellular substances which would 

 produce a change in the tumor cell and make it capable of exert- 

 ing a chemotactic effect upon splenic mesenchyme in general, 

 the embryonic splenic mesenchyme would then exhibit a phago- 

 cytic and digestive activity. The study of such grafts, how- 

 ever, failed to reveal any effect of the adult splenic necrotic 

 tissue upon the tumor cells. 



In these grafts, as in tumor-necrotic adult splenic grafts, 

 tumor cells themselves occasionally exercise a phagocytic ac- 

 tivity against the necrotic splenic adult tissue. It would be of 

 interest to graft tumor with adult splenic tissue, previously 

 thoroughly washed out by saline solution, in order to free it 

 from the presence of any possible injurious extracellular sub- 

 stance and to see whether the phagocytic and digestive activity 

 of the adult splenic mesenchyme against the transplanted tumor 

 cells would still persist. 



These two series of experiments clearly show that the adult 

 splenic tissue, frozen or kept at a low temperature from three 

 to seven days or left in the incubator from one to three days, 

 does not contain substances which can change a tumor cell in 

 such a way as to make it exert a chemotactic action on a mesen- 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 2!), NO. 4 



