470 Second European Journey 



its host," as Borrel paraphrases my thought. And this is what I would ask 

 all cancer workers to reconsider, namely, whether in malignant tumours of 

 man and animals it may not be possible that there occurs a concealed para- 

 site, which, from its vantage ground within the cell, stimulates the nucleus 

 into abnormal division, and passes over into the daughter-cells during this 

 division, and so on, ad infmitum, as is the case in crown-gall. 



No harm will be done if my hypothesis is found not to have any founda- 

 tion in fact, but if I should happen to be right, then great results must 

 follow. For, once the cause of cancer is ascertained, better methods of 

 prophylaxis will immediate suggest themselves, and the remedy may even- 

 tually follow. 3 



Crown gall was believed to be a cancer in plants and Bacterium 

 tumejaciens its parasitic cause. He had supplied cultures of this 

 organism to European and American scientists, some of whom 

 had reproduced the disease on sugar beets and other plants: 

 Jensen of Copenhagen, Peklov of Prague, and von Dungern of 

 Heidelberg. Dr. Peklov had sent him " a photograph of an inocu- 

 lated sugar-beet, on which [was] shown as typical a tumour as 

 any we have produced in the United States," Smith said. " Others, 

 following my directions, have isolated the parasite for themselves, 

 and with it have reproduced the disease, e. g. Clayton Smith in 

 California, J. Bolle in Austria, and Pole Evans in South Africa." 



He realized that the history of cancer research was strewn 

 " with wrecks of parasitic theories." But the difficulty, he believed, 

 had been that " substantial proof " upon an experimental basis 

 under an adequate hypothesis of cancer development had been 

 lacking. A fundamental study of pathological growth, made in 

 plants of tumors in plants, was offered to medical science in the 

 belief that experimental research in animal cancer might benefit. 

 Plants were more abundantly available and easier of manipu- 

 lation than the higher animals. " Cancer," he said, " has stood 

 for many years a great sphinx-like problem of pathology, defying 

 solution. Indeed, now that the aetiology of syphilis is solved, we 

 may say it is the last great problem of human pathology to remain 

 in a cloud of uncertainty." 



In 1911 Hideyo Noguchi, youthful and distinguished Japanese 

 pathologist working at the Rockefeller Institute for Medical 

 Research, had isolated in pure culture from the brain and cord 

 Treponetna pallidum, cause of syphilis. He made possible 



^ Proc. 17th Inter. Cong, of Med., London, Aug. 1913, and reprint, p. 17 



