6 4 



Scientific Proceedings (36). 



38 (448) 



Resistance to the growth of cancer induced in rats by 

 injection of autolyzed rat tissue. 1 



By Isaac Levin. 



\_From the Department of Pathology of Columbia University, at the 

 College of Physicians and Surgeons. ,] 



It is a fairly well established fact that an immunity, or rather 

 a resistance to the growth of a transplantable tumor may be 

 induced in white mice and rats by artificial means. This acquired 

 resistance is of a peculiar type and is not similar to the usual form 

 of the anti-bacterial immunity. Clowes and Baeslack's assertion, 

 that the serum of recovered mice cures cancer in other mice, has 

 received no confirmation. Nor has any other known method of 

 detecting the existence of immunity in an organism met with 

 success in the animals refractory to growth of implanted cancer. 



While the best manner of immunizing an animal against tumors 

 consists in a previous unsuccessful inoculation of a tumor, this 

 resistance does not appear to be specific. Ehrlich observed that 

 an animal made resistant to a certain class of tumors, carcinoma 

 for instance, is also resistant to the growth of an implantable sar- 

 coma. Furthermore, a resistance may be artifically induced by 

 previous inoculation of normal tissue of the same species of 

 animals. Michaelis produced such an immunity by injection 

 of normal mouse liver ; Bashford by injection of blood or washed 

 blood cells, but not by blood-serum ; Schoene with different 

 embryonic tissue ; Bridre with liver and spleen. 



All these methods of immunization seemed to be successful 

 only when uninjured cells constitute a part of the substances used 

 for the injections. Blood-serum, deprived of the cells, or normal 

 or tumor tissue heated or crushed and frozen, does not induce 

 any resistance — as was shown by the investigations of Michaelis 

 and Haaland. 



In view of all these facts, the opinion seems to prevail that an 

 artificial immunity or resistance can only be induced by the inoc- 



1 This research is conducted at the expense of George Crocker Special Research 

 Fund. 



