DISCOVERY OF PROTEIN PRINCIPLE IN THERAPEUTICS 109 



theory, and the mental associations that made its elaboration 

 possible, represented a lifetime of study; and the sequential de- 

 velopments, to which I am about to refer, were equally con- 

 ditioned on antecedent knowledge acquired through years of in- 

 vestigation. It is in this connection that I call to mind the 

 otherwise unrelated incidents just cited. 



In particular, I would recall that the thing that impressed me 

 most in the visit to Ehrlich, above mentioned, was the room in 

 his laboratory where endless series of glass jars contained can- 

 cerous mice. Ehrlich himself at the moment was all enthused 

 over his tentative success with salvarsan, and he made but inci- 

 dental reference to the cancer mice, but I felt that this was the 

 problem that would next engage his attention a problem, in- 

 deed, that had been interrupted by the other studies. With 

 peculiar interest, then, I learned a little later of the experiment 

 in which he had attained at least tentative results in the devel- 

 opment of a chemical combination, including selinium, that ap- 

 peared to have a selective action on cancer cells ; a work dupli- 

 cated, independently, I believe, by Wassermann, in Berlin. 



These observations, and the still newer work of Wassermann, 

 in which he had endeavored to diagnose the presence of cancer 

 by tests applied to the blood, were fresh in my mind when I 

 observed the patients, and studied the photographs, at Dr. Kelly's 

 sanitorium there in Baltimore. I had also in mind the recently 

 reported experiments of Dr. Leo Loeb with colloidal copper in 

 the treatment of cancer. And I was, of course, familiar with 

 various tentatives in cancer treatment that had been made with 

 biological products, as admirably summarized in Dr. Bainbridge's 

 book of which just at this time I received a presentation copy 

 from the author. In particular I had followed with interest the 

 work of Hodenpyl, partly because I chanced to know personally 

 the patient from whom the ascitic fluid used by him with such 

 thought-provocative results was removed. 



And as I linked and co-ordinated these various items of knowl- 

 edge, the thought that was paramount in my mind was that, be- 

 yond preadventure, it had been demonstrated that the cells of a 

 malignant neoplasm, notwithstanding their similarity to normal 

 cells, have essential differences that bring them within the pos- 

 sibility of selective action on the part of physical or chemical 

 agencies. The fact that all the methods of practically treating 

 cancer used hitherto had proved only tentative or utterly dis- 

 appointing; the fact that the cancer mass seemingly dispelled 

 by radium treatment might recur and grow with renewed and 

 fatal activity these facts seemed to me altogether subordinate 

 to the great central fact that the cancer cell could, in some 

 instances, be caused to undergo seemingly autolysis through the 



