254 



muscular tissue, stored 2—3 weeks in the refrigerator, the 

 mass of the tissue being increased very much during llial. 

 time. It can therefore be conckided, thai the sarcoma. 

 can be cultivated indefinitely this way. The strain now 

 under cultivation is about 2 years old. 



There is every reason to belive, that other malignant tumor 

 cells can be cultivated the same way. The human sar- 

 comata will be tried as soon as material can be oblained. 



Experiments of reinoculalion of the R o u s"s chicken 

 sarcoma from cultures have been undertaken all the limo 

 during the cultivation. It was observed that one single 

 culture inoculated subculaneously on the breast of big 

 chickens showed to be sufficient to develop a tumor which 

 4—6 weeks after causes the death of the animals. Fig. (52 

 represents a section of a tumor from a big chicken which 

 has been inoculated with only one culture of sarcoma cells 

 which had undergone about 40 passages in vitro. Reinocu- 

 lalion of tumor tissue from cultures have been performed 

 by L a m b e r t and H a n e s, R h. E r d m a n n. but the malig- 

 nant tissue had been cultivated only for a ahori time in 

 vitro. 



We have learned from these experiments, that it is pos- 

 sible to cultivate a strain of malignant tumor cells,, the 

 Rous sarcoma, indefinitely outside the body the cells still 

 maintaining their malignant character. We are dealing with 

 cells, which have a decidedly different physiological cha- 

 racter than the normal tissue cells. 



Numerous problems for investigation are opened up by 

 this method. The interesting question of the relation of the 

 stroma cells to the malignant cells, which R h. E r d m a n n 

 1^3) has pointed out, will possibly be cleared up by this 

 method, by which it is possible to obtain strains of the 

 malignant cells from only one cell. 



A method is developed, by which it is possible to cul- 

 tivate sarcoma cells of the type of R o u s's chicken sarcoma, 

 indefinitelx outside the body, which hitherto has been un- 

 successful. 



