536 Crown Gall-Animal Cancer Analogy 



tumors, Smith used a flask culture technique. Various gall-forming 

 fungi and bacteria could be cultivated in flasks " on simple culture 

 media in any desired quantity and their products determined with 

 a minimum of labor. This, rather than the analysis of tumors," 

 was the proper procedure. He gave as his reasons ^^ that 



the cells of a tumor are only the cells of a plant or animal grown under an 

 abnormal stimulus, which stimulus, it is very likely, is not only very minute 

 in quantity but also used up during the growth of the tumor cells, that is, 

 converted into something quite different and entirely inoffensive. For this 

 reason analyses of tumor tissue should give only about the same kind and 

 quantity of products as normal tissues in which there is an equally rapid 

 movement of food-stuffs, and in which there is an equally rapid growth, 

 and this is about what tumor analyses thus far have shown. In flask cul- 

 tures, on the contrary, the products of parasitic growth accumulate and can 

 be locked up for future study. 



From 1911 to 1917 he prepared flask cultures of various sub- 

 stances produced by various strains of Bacterium tumefaciens out 

 of river water, peptone and grape sugar, " substances corre- 

 sponding to or approximating those which occur naturally in the 

 cells of the plant." ""^ These were sent to expert organic chemists 

 of the Department of Agriculture. But, before submitting them, 

 he tested each culture as to purity by pouring Petri-dish agar plates 

 and as to pathogenicity by inoculating susceptible plants. From 

 substances found present in the culture flasks and not in the con- 

 trols he, with the aid of the chemists, determined " the most 

 interesting . . . products of a cancer parasite, or, if one prefers 

 so to express it, of a schizomycete which is the cause of a plant 

 tumor possessing many features in common with animal cancers." 

 These subsances were " for the most part " ammonia, amines and 

 fatty acids." 



Proceeding on the hypothesis that " the parasite acts through 

 its excretions " similarly as " most communicable diseases are due 

 not to the parasites but to their toxins," ^^ he continued his study 



** Mechanism of overgrowth in plants, op. cit., 437-438. 



'^^ Idem, 438 (flask culture technique explained) ; Chemically induced crown galls, 

 op. cit., 312 (Smith described the " very simple culture media [as] in flasks of 

 distilled water containing 1% dextrose and 1% peptone with a little calcium car- 

 bonate added to neutralize any acids formed and thus to favor long continued growth 

 since the crowngall organism is very sensitive to its own acid products.") 



" Chemically induced crown galls, op. cit., 312-313; Mechanism of overgrowth in 

 plants, op. cit., 439. 



''^ Production of tumors in the absence of parasites (New Orleans address), op. 

 cit., 4. 



