532 Crown Gall-Animal Cancer Analogy 



a clear-cut way as to leave no doubt whatever. Many years ago I got what 

 I considered to be small sarcomatous tumors in fish, using the crown gall 

 organism, but some of these receded and I never knew for certain that all 

 would not have receded if I had left them longer, that is, it is so difficult 

 to be sure that a proliferation confined to the injected part is not merely 

 a response to the irritation which later on will all be absorbed. If I had 

 got definite secondary tumors in my trout, then I would have thought I had 

 something, but these I never got. In the same way (1914) I started a 

 series of inoculations on salamanders and I got one definite adeno-carci- 

 noma of the intestine, but that did not convince me, since " one swallow 

 does not make a summer," to quote the proverb. It may have arisen 

 naturally and not been due to anything I did. 



Dr. Smith remained preeminently throughout his life a student 

 of tumors in plants. His paper on appositional growth in crown 

 gall tumors and in cancers was addressed to cancer research men; 

 in fact, as we shall see, its first real presentation was before the 

 American Association for Cancer Research. He, however, care- 

 fully qualified his purpose: 



I am the more inclined to publish my observations on appositional 

 growth in these plant-tumors, -^ because of very positive statements by many 

 cancer specialists, from Waldeyer, Cohnheim and Virchow down to Hauser, 

 Krompechcr, v. Hansemann, Petersen, Cornil, Fabre-Domergue, Menetrier, 

 and others, as to the occurrence of appositional growth in carcinoma, and 

 because in many respects crown galls are better adapted to the study of 

 this phenomenon of growth by apposition than animal tumors, not only 

 because we know them to be due to an intracellular schizomycete so that 

 there is a definite reason for such growth, but because they can be repro- 

 duced at will and collected for examination at any period of growth, and 

 finally, because there are no migratory cells to confuse the picture. 



As early as 1908 Dr. James Ewing, professor of pathology 

 of Cornell Medical School and director of cancer research of 

 Memorial Hospital, New York City, had been among those medical 

 scientists who encouraged Smith to make, with crown gall, a 

 fundamental study of pathological growth.'' Ewing later became 

 a sincere, honest, and forthright critic of Smith's theories. Among 

 other points, he thought that Smith, as a plant scientist, went too 

 far in his crown gall-cancer analogies.'- On November 9, 1921, 



^"Appositional growth in crown-gall tumors and in cancers, op. cit., 4-5. 



"^ See, A. J. Riker, E. Spoerl and Alice E. Gutsche, Some comparisons of bac- 

 terial plant galls and of their causal agents, Botanical Review 12(2): 59-60, Feb. 

 1946. 



''- Told author by Dr. Riker who was told so by Dr. Ewing. 



