438 VERA DANCHAKOFF 



chick against the Ehrlich sarcoma cell is a specific reaction 

 strictly limited to the substratum used. Other series of experi- 

 ments were made, in which other tumors were grafted on the 

 allantois in mixture with adult splenic mesenchyme. Tumor 

 180, carcinoma 63, and the Jensen rat sarcoma were thoroughly 

 mixed with the splenic tissue of an adult chick and grafted on 

 the allantois. A destructive mesenchymal reaction similar to 

 that against the Ehrlich sarcoma has been observed only against 

 tumor 180. Though similar to that obtained against the Ehr- 

 lich sarcoma cells, the reaction against tumor 180 has never 

 been found as pronounced, unless quantities of spleen two or 

 three times greater than the amount of tumor were grafted. 



3. GROWTH OF THE EHRLICH MOUSE SARCOMA IN THE CHICK 



ALLANTOIS 



Changes of the allantois at a late stage of incubation as factor 

 of tumor recession at this time 



The vascular membrane found in the chick egg beneath the 

 egg-shell membrane, commonly called the allantois, consists in 

 fact of two membranes, the serosa and the allantois. The mem- 

 branes fuse with each other by their mesodermal surfaces and a 

 rich net of allantoic capillaries grows through the ectoderm of the 

 serosa and expands over its surface as the respiratory embryonic 

 organ (Danchakoff^^). The rich vascular net which, in later 

 stages (after 8 to 9 days of incubation) is in direct contact with 

 the egg-shell membrane, assures the nutrition of the graft. 



Growths of EhrHch sarcoma grafts have been studied from one 

 to thirteen or fourteen days after grafting. Tumors not older 

 than two weeks have been used, in order to avoid- as far as pos- 

 sible inclusions of necrotic masses in the grafted material. A 

 microscopic study of tumors at this age has shown, however, 

 that small necrotic areas were frequently present, especially in 

 the center of the tumor. Before grafting the tumor was forced 

 through a syringe with a sieve bottom, the grafted material con- 

 sisted always of living cells together with an inconsiderable 

 amount of dead cellular material. Small particles of this mash 



