306 Resistance to the Implantation of Maligna7it JSeiv Growths. 



The assiimption of an " atreptic " immunity to cancer has been applied to 

 phenomena wliich are more naturally explained as due to an active resistance 

 induced against cancer-cells. The assumption of a special form of immunity, 

 " atreptic " in nature, is also incompatible with the fact that re-inoculation is 

 successful in direct relatioir with the rapidity of the growth of the successful 

 primary inoculations, and with the i'act that when resistance to re-inoculation 

 is present, it is identical with that active form of resistance induced in 

 normal animals by the absorption of living tissue, either tumour or normal. 



The assumption of an " allergetic " immunity to cancer is applied to what 

 is really an active immunisation against the tissues of a strange species of 

 animal. 



The immunity induced in rats by the inoculation of mouse cancer, or by 

 similar heterologous inoculations in the case of other animals, is absolutely 

 distinct from the resistance induced against cancer of the same species to 

 which it has no direct*relation. 



Only one form of active resistance to the implantation of cancer from one 

 animal to another has as yet been demonstrated to exist. This resistance 

 follows only upon the absorption of living tumour tissue or living normal 

 tissue of one ardmal, when introduced into another animal of the same 

 species. So far as yet elucidated, it consists primarily in an inhibition of the 

 specific chemiotactic powers which cancer-cells exercise upon the connective 

 and vascular tissues of the host. This single explanation harmonises all the 

 observed facts, and should rid the experimental study of cancer both of 

 confusion and error. It may be pointed out that investigations, such as 

 those described in this paper, bear upon the nature and biological behaviour 

 of cancer-cells ; but that they do not admit of any inferences as to possible 

 methods of treating the disease. 



REFERENCES. 



(1) ' Zeitsclir. f. Aerztlichc Foi thikliuig,' No. 7, April, 1!KK). 



(2) ' Vorhandl. il. Doutsch. Path. Gescll.,' 1908. 

 (:J) ' R^)y. S(.c. Troc.,' ]}, vol. 78, 190G. 



(4) Tliird Scientific Report of the Imperial Cancer Roseaicli Fund, l!K)8. 



(5) ' Zcitschr. f. Immunitiitsfor.sclmng,' vol. 1, Heft 4, 1!)0!). 



(6) Jenfien, ' Ceiitrail). f. Bacteriol.,' vol. 34, 1903. 



(7) ' Roy. Soc. I'roc.,' vol. 73, 1901. 



(8) Second Scientific R.eport of the Tmjierial Cancer Resoanli l''ini(l, Fart II, 1905. 



(9) ' Roy. Soc. Froc.,' H, vol. 79, 1907. 



(10) 'AH), a. (1. Koniglichen InHtitiit. f. Exp. Therapie,' Heft I, 190(1. 



(11) 'Zcitschr. f. luinuinitiitaforschung,' vol. 2, lloft A, 1909. 



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(13) 'Roy. Soc. Fioc,,' 11, tliis vol., supra, p. 293. 



