572 Crown Gall-Animal Cancer Analogy 



duced sarcomata has been extended. "° Such a discovery as that 

 made by John J. Bittner in 1936 that a cancer virus may be trans- 

 mitted by a susceptible mother to her offspring through her milk, 

 a conclusion still very much in doubt/^*' finds adherents of the 

 virus theory of cancer etiology defending the hypothesis and as 

 many, perhaps more, equally qualified cancer authorities opposing 

 it. Smith contributed knowledge to a research period from which 

 much of the modern, more advanced knowledge has emerged, or 

 on which in considerable part it has been based. When we con- 

 sider the subject of tar cancers, more will be said about carcino- 

 genic agents. But it may be suggested now that, had not the 

 chemical compounds been made available, Bacterium tiimefaciens, 

 as such an agent, likely would have found more of a place in 

 cancer research laboratories as well as in laboratories of plant 

 pathology. 



Several times Dr. Smith in writings or utterances had expressed 

 confidence that scientific proof would settle the question whether 

 a parasitized cell would continue to grow if the parasite died out, 

 lost virulence, or was removed. In recent years, from research 

 in crown gall, an answer has been made available. Dr. Philip 

 R. White of the Lankenau Hospital of Philadelphia and Dr. 

 Armin C. Braun of the department of animal and plant path- 

 ology of the Rockefeller Institute, with the use of a plant tissue 

 culture technique, and taking advantage of the native sterility of 

 secondary crown gall tumors on sunflower, have isolated and 

 cultivated in vitro tissues of varying degrees of malignancy. Some 

 of these have been shown to be " capable of producing bacteria- 

 free crown-gall tumors when grafted back into sunflower or arti- 

 choke after prolonged multiplication in vitro. The tumor-forming 

 capacity has thus been segregated from the bacteria and the tumor 

 can be studied and its metabolic processes followed in the absence 

 of the original inciting agent." "^ In 1942, while Dr. White was 

 yet with the department of animal and plant pathology of the 

 Rockefeller Institute, he and Dr. Braun published in Cancer 

 Research "' an important study, the product of their researches and 



^^"^ See, Leonell C. Strong, A new influence on chemically induced sarcomata, 

 Science 108(2816): 688-689, Dec. 17, 1948. 



^^^ Cbr\r!cs Oberling, The riddle of cmcer, op. cit., 82, 162. 



"''Philip R. White, Plant tissue cultures, Ann. Rev. of Biochemistry 11:624, 

 1942. See'also Science 94(2436): 239-241, Sept. 5, 1941. 



"'2(9): 597-617, Sept. 1942. 



