68 



Scientific Proceedings (97). 



organism, and it exercises this power from the earliest stages of 

 embryonic development. We know little of its response to foreign 

 proteins and to normal living cells. We do know, however, that 

 it has no power over, and, therefore, no injurious effect upon, 

 tumor cells. Tumor cells will grow amongst, and together with, 

 mesenchymal cells. 



The digestive power of adult mesenchyme (fibroblasts, clas- 

 matocytes, splenic cellular reticulum) is much greater. We see 

 fibroblasts and clasmatocytes ingest red blood-corpuscles after 

 hemorrhage, and particles of a disintegrating nerve after section 

 of a nerve trunk. Under normal conditions macrophages in the 

 spleen are actively engaged in the phagocytosis of red blood- 

 corpuscles. Artificially separated cells of the splenic mesenchyme 

 may contain dozens of red and white blood-cells in their cytoplasm ; 

 or, again, fibroblasts in a culture may be seen loaded with particles 

 of artificial medium. The ingested substances undergo an in- 

 tracellular digestion. 



Moreover, the adult mesenchyme of the splenic cellular reti- 

 culum, when compared with that of the embryo, is found to have 

 acquired a new property. Embryonic splenic mesenchyme in 

 the chick does not show any inhibiting power even as late as the 

 hatching period, much less any destroying power over any kind 

 of tumor cells. Tumor and splenic mesenchyme of a hatching 

 chick thoroughly mixed will grow on the allantois well, as though 

 transplanted independently. Splenic mesenchyme of the adult 

 fowl, on the contrary, possesses the power of checking the Ehrlich 

 mouse sarcoma (in its present phase of growth in the Crocker 

 Laboratory), and in retarding the growth of the very malignant 

 mouse sarcoma 180. The photographed preparations (demon- 

 strated by lantern slides), show a curious relationship developing 

 between the mesenchymal part of the adult tissue and the tumor 

 when these are thoroughly mixed together and grafted on the 

 allantois of a 7- or 8-day chick embryo. The tumor cells are not 

 injured mechanically by this procedure, nor do they show any 

 signs of an immediate injurious action by the enzymes which are 

 known to be present in the spleen, for intensive growth of tumor 

 mixed with spleen is observed during the first two, and sometimes 

 three days of further incubation of the egg. 



