528 Crown Gall-Animal Cancer Analogy 



which produces acids and alkali in flask cultures and probably also inside 

 the cells as a result of its metabolism), and (3) I can now bring about the 

 same results in the absence of parasites and their products by limiting the 

 intake of oxygen, thus compelling the cells themselves to manufacture the 

 stimulus which leads to the development of hyperplasias. I can conceive of 

 this taking place only as the result of an anaerobic cell respiration acting 

 on the youngest, most active cells of a tissue; but there must be always 

 some oxygen of the air present, otherwise there will be complete asphyxia- 

 tion of the tissues, as happened in my first experiments. Probably over- 

 growths due to freezing and to mechanical injuries will also be found to 

 depend on local interference with cell respiration. 



The most striking tumors are obtained by inoculating the crown gall 

 organism, Bacterium tiimejaciens. Some of these are simple tumors and 

 others are tumors containing roots and shoots. Some also show the begin- 

 ning of secondary tumors, and in the embryomas the invasion of tumor 

 tissue into the embryomatous parts (young roots and shoots). 



His diary of May 1, 1920, revealed that at New Orleans he 

 exhibited photographs of tumors produced in the absence of 

 parasites and live specimens of inoculated crown gall on sugar 

 beet, cassava, castor oil plant, tomato, geranium, and Bryophyllum. 

 Embryomas of the last three plants were demonstrated. The 

 tomatoes illustrated root-bearing tumors, and the Pelargonium 

 and Bryophyllum tumors bore leafy shoots. There was praise of 

 his work in the discussion. The next problem had been indicated 

 in this address and in preceding papers: how and by what method 

 did tumor cells invade normal tissue, in crown gall and in animal 

 cancer.^ In crown gall research, thus far at least, Bacterium tume- 

 faciens had not been cultured out of the gall tissue, and it was 

 believed almost beyond doubt that the action of the parasite and 

 its by-products was confined to the cells; in other words, the 

 disease began in the cells intracellulary and, spreading by contact 

 of one cell with another, overcame in its invasion one cell after 

 another until at last tissue and all organic substances fell subject 

 to the disease so far as the disease spread within the plant body. 

 This was the scientific view adhered to by Dr. Smith at this time. 



In July 1920 he purchased and began to read several important 

 texts on human pathology: " the part on tumors," he noted in 

 his diary. These texts were Aldred Scott Warthin's edited and 

 translated version of Ziegler's General Pathology and Francis 

 Carter Woods' revision of Delafield and Prudden's work on the 



