Immunity to the Growth of Cancer. 



107 



Conclusions. 



1. Dogs injected with 5 c.c. of tuberculin or of the unconcen- 

 trated filtrate become sensitized to tuberculin, and an injection of 

 tuberlin (1 drop in some cases) given the following day produces a 

 drop in arterial pressure. 



2. The depressor substance is not affected by heat up to and 

 including 100 0 C. during a period of one hour. 



3. If the tuberculin is kept at 105 0 C. for one hour the depres- 

 sor may be lost or greatly diminished. 



4. The results of the serum of tubercular calves injected into 

 the sensitized dog seem to indicate that the method outlined in our 

 previous paper can be used for the early diagnosis of tuberculosis. 



5. This depressor substance seems to be different from the 

 depressor substance of tuberculin in that the tuberculin depressor 

 substance is much more stable ; while the depressor substance of 

 tubercular serum may be lost when the serum is kept in the ice 

 box. 



6. These experiments possibly give us a method for standard- 

 izing tuberculin by noting the minimal quantity which will cause 

 a reaction in blood pressure. 



66 (476) 



Immunity to the growth of cancer induced in rats by treat- 

 ment with mouse tissue. 1 



By ISAAC LEVIN. 



[From the Department of Pathology of Columbia University, at the 

 College of Physicians and Surgeons."] 



The opinion prevails among investigators that resistance to 

 growth of tumor can be induced only by treatment with tumor or 

 normal tissue of the same animal species. In the course of a 

 study on different phases of atreptic immunity, a series of experi- 

 ments was undertaken with the aim in view to find the means 

 whereby mouse tumor may be made to grow on a rat and vice 

 versa. Ehrlich, in his so-called zig-zag transplantations, has 

 shown that such a tumor of a mouse inoculated into a rat grows 

 normally for eight or ten days and then ceases its growth and be- 



^his research is conducted at the expense of the George Crocker Special Re- 

 search Fund. 



