SPECIFIC TREATMENT OF CARCINOMA. 393 



excised one testicle of a rabbit and having injected an extract of the organ into 

 the same animal, were able to demonstrate the development, in the treated 

 rabbit, of a condition of hypersensitiveness. According to some experiments of 

 Gorowitz, reported by von Dungern, a condition of hypersensitiveness to the 

 cancer proteids can be demonstrated in the patient bearing the tumor. This 

 condition shows itself in an increased reaction, as compared with that produced 

 by injection into normal individuals, upon subcutaneous inoculation with extracts 

 from the patient's own tumor. No increased reaction could be elicited in these 

 cases by the injection of extracts from the tumors of others. 



At first thought it "vyould seem improbable that an organism could 

 be induced to elaborate substances capable of destroying its own tissues. 

 The publications of Metalnikoff;, von Dungern and Hirschfeld^ and 

 Gorowitz, however, demonstrate just this power. It can still be ob- 

 jected that in the experiments reported by these observers, the injurious 

 effect of the antibodies was exerted not upon the cells of the organs 

 in situ, but only when these had been isolated in vitro. In reply to 

 this objection, attention may be called to the fact that the normal 

 epithelial cells are separated from the other tissues of the body by a 

 dense basement membrane, the function of which can be to prevent, on 

 the one hand, the entrance into the circulation of the specific epithelial 

 cell products, and, on the other hand, the access to the epithelial cells 

 of any specifically inimical substances carried by the blood. The opera- 

 tion of the latter assumed function would explain the immunity to the 

 destructive action of the complex cytotoxins present in the blood, which 

 is enjoyed by the spermatozoa in situ, in the case of the rabbit treated 

 with its own testicular tissue. 



Entirely analogous to such a physiological condition is the fact that 

 complement is normally not present in the aqueous humor of the eye. 



One of the earliest evidences of beginning malignant change in 

 epithelium is the disappearance of the basement membrane at the point 

 of invasion of the underlying tissue. In the further course of the 

 disease, this peculiarity is maintained, and the tumor cells are thus 

 brought into closer relationship with the blood than were the normal 

 parent cells. 



The assumption of a protective -function exercised by the basement 

 membranes, taken together with the fact that in all malignant tumors 

 this protective membrane is wanting, would sufficiently explain why 

 the tumor cells in the immunized individual may be destroyed by 

 specific cytotoxins in the blood, whereas the noun ally situated epithelium 

 is spared. 



The experiments of von Dungern upon the sarcoma of the wild hare 

 would seem to stand in direct contradiction to the hypothesis here 

 advanced. It is to be borne in mind, however, that the immunity 

 demonstrated by him against the sarcoma was always against inocula- 

 tion of tumor tissue taken from another animal, and had in every 



