564 Crown Gall-Animal Cancer Analogy 



entire revision of views as to the nature of tiie disease." "^ In his 

 textbook (1920)^°- he had said that Jensen's belief in an auto- 

 nomous growth of parasitized cells without the aid of the bacteria, 

 that is, in their absence, was " a subject for further consideration.". 



Biologist M. C. Marsh of the New York State Institute for 

 Study of Malignant Disease answered on February 3, 1924, an 

 inquiry from Smith about some of his experiments made with 

 mice along this line. " Yes," said Marsh, " we are getting 

 interesting results from mice. That quite expresses it. They add 

 to, rather than subtract from, the difficulties, and indicate the 

 need of long drawn out replanned experiments. The absence 

 of worms does not stop the tumors from developing." Marsh's 

 studies on breeding and the hereditary aspects of cancer etiology 

 interested Smith for years; he mentioned them in several addresses, 

 and Marsh was now planning experiments to " continue genera- 

 tions of worm-free mice indefinitely." 



At the 1925 cancer research association meeting. Dr. Smith 

 entered into the discussion which followed the reading of a paper 

 by Dr. Leonell C. Strong on " Genetic deviations within the 

 transplantable tumor cell." He urged: "^ 



It would be interesting if it could be made out definitely that through 

 irritation certain factors or structures inside the cell are destroyed or 

 weakened. I have for a long time thought it might lead to a solution of 

 the cancer problem, if the cytologist could make out changes in the cell 

 which would give to its progeny an aberrant course. Boveri called attention 

 to such changes. 



Irritations, as a factor leading to cancer in susceptible indi- 

 viduals, were believed by Smith to be of numerous kinds."* 

 Repeated tar paintings fell in this category, and these are yet to 

 be considered more fully. Woundings due to repeated applica- 

 tions of arsenic, anilin, paraffine, and other substances were 

 another. The latter has significance in crown gall study as well 

 as cancer. In 1938, in a study of " Growth Substance and the 

 Development of Crown Gall," "'^ Dr. Riker, Dr. B. M. Duggar, 



^"^ Synopsis of researches of Erwin F. Smith, op. cit., 39-40. 

 ^"^ b2tro. bad. dis. of plants, op. cit., 569. 

 ''"^ jour. Cancer Research 9: 509, 510, 1925. 



'^'^*']our. Heredity (Organ of the American Genetic Assoc), 16(2): 61-62, Feb. 

 1925. 



"■""•jour. Agric. Res. 57(1): 21-39, July 1, 1938. 



