524 Crown Gall-Animal Cancer Analogy 



has been known for a long time to throw adventive shoots from leaves 

 and stems (a very queer phenomenon) but nothing was known as to the 

 cause of this peculiar behavior. I began to experiment with it thinking it 

 might throw some light on non-cancerous tumor-cysts and the like. I find 

 the shoots arise from the skin of the plant and that by certain forms of 

 stimulus I can get them in great numbers at will. They are not vascularized 

 into the mother at least not on the start, and most of them never were, 

 and consequently they die in course of a few weeks. I have sometimes had 

 as high as several thousand of these baby plants develop from a single leaf 

 while still attached to the mother plant. 



Jensen of Copenhagen (the mouse cancer man) has published this year 

 (in Danish) a long paper on Crown Gall of plants summing up his 

 observations and experiments of the last ten years, but also discussing 

 critically the work done on it here in the Department of Agriculture 

 especially as it bears on the question of animal cancer. I have had the 

 whole paper translated, and find it so very stimulating that I wish it could 

 be published somewhere in English. The enclosed excerpts =* will show 

 what he thinks of some of my notions. I have always believed that the pull 

 of heredity is so strong that as the disturbing factor is removed (bacteria 

 in case of crown gall) the tumor cells will cease to behave abnormally 

 whereas Jensen develops the very interesting idea that once the bacteria 

 have converted normal cells into tumor cells the microorganisms may then 

 die out, while the cells still retain and transmit their acquired characters. 

 In other words, he believes in the transmission of acquired characters while 

 I do not, or perhaps I should say, don't think there is as yet any good 

 experimental evidence of it, for I would keep an open mind. You may 

 have the whole paper to read if you wish. 



Dr. CuUen answered, expressing much interest " in the memo- 

 randum ... of Professor C. O. Jensen's work on Animal Cancer." 

 He and Smith many times discussed various aspects of problems 

 of cancer research. 



Smith was now studying the beginning and middle phases in 

 the production and development of tumors in plants. Some of his 

 experiments were made with the aid of bacterial infection: and 

 some by simple woundings and various experimental interruptions 

 of normal physiological functioning and healing. In each experi- 

 ment, he v/as interested in determining the minimum stimulus 

 necessary for tumor production and tumor growth. He wanted, 

 for purposes of his crown gall-animal cancer analogy, to arrive 



^ These, or similar, excerpts were included in Smith's address, Twentieth century 

 advances in cancer research, Jour. Radiology 4(9): 299, Sept. 1923. Jensen's paper 

 was described in a letter to Dr. Gaylord as " Investigations concerning some tumor 

 resembling growths in plants," Serum Laboratory Rep't 54 or 59, Copenhagen, 1918. 



