394 COCA AND OILMAN. 



instance been produced by injections of sarcoma material derived from 

 a similarly foreign source. In most cases the biological relationship 

 between the tissues of the animal to be immunized and that of the 

 sarcoma was a comparatively distant one, and even in the few experi- 

 ments in which the immunity seemed to be demonstrable in an animal 

 of the same species as the one in Avhich the tumor originated, the material 

 used both for immunizing and for testing the immunity had been growing 

 for some time in a biologically foreign organism. 



However, if it is found to be possible to immunize an individual 

 against his own sarcoma, then, of course, the hypothesis here suggested 

 will have to be modified. 



Another explanation of this apparently paradoxical phenomenon has 

 been suggested by von Dungern,* namely, that the tumor cells may be 

 so altered in biological character from the normal parent cell that the 

 antibodies elaborated against the former may be specifically unrelated 

 to the latter. The superioi'ity of malignant tissue over normal tissue 

 in its power of inducing immunity against tumors would speak in favor 

 of this view. 



Theoretical speculations as to the probable outcome of an experiment, 

 while often of value in determining the manner of procedure, are usually 

 less satisfactory than the experiment itself. 



In order to immunize a cancer patient against his own cancer, it is 

 necessary, according to our present knowledge of immunity, to inject 

 into his body some of the tumor tissue or an extract from the tissue. 



Similar attempts to induce, in human beings, by inoculation an active 

 immunization against their own tumors have already been made. The 

 first of these were reported by von Leyden and P. Blumenthal." 



An exact description of the technique of their treatment does not appear in 

 their publication. In none of their cases did they produce a complete cure 

 of the disease, although they believed that in three instances, as a result of the 

 treatment, metastases were prevented, and affected lymph glands reduced in size. 

 These experiments were apparently discontinued. 



Von Dungern " in his paper, "Untersuchungen uber das Wesen der Immunitat 

 gegen Karzinom," read June 4, 1909, in Vienna, stated that such experiments 

 had been instituted in the cancer hospital at Heidelberg, and Ranzi, in the 

 subseqiient discussion, referred to his ovra treatment of a few tumor patients 

 \^•ith carbolized extracts of their own tumor tissue. So far as we are aware, 

 neither of these two investigators have made any report as to the results of 

 their treatment. 



In our earliest experiments we were apprehensive as to whether we 

 might not reinfect the patient with cancer at the point of injection, and 

 also that lai-ge quantities of cancer extract might be directly toxic if 



* Oral communication. 



^Deutsche med. Wchnsch. (1902), 28, 36. 



'Centralhl. f. Bait. etc. Kef. Beilage zu Abt. I. Jena (1909), 44, 57. 



