Last Work. Final Honors 585 



purpose was to ascertain tlic exact amount of acidity in tumor 

 juices over and above normal plant juices scaled down to phenol- 

 phthalcin neutrality, to determine the ranges of tolerance of 

 various plants to acids and alkalies, in other words, to fix for 

 each set of phenomena the so-called pH factor at which, among 

 other points, bacterial growth and gall development will be 

 inhibited. In 1923, at the annual meeting of the American Asso- 

 ciation for Cancer Research, Dr. Smith had been elected vice 

 president of the organization, and in 1924 he had been elevated 

 by the association's council to the office of president. This took 

 place at its seventeenth annual meeting which was held that year 

 at Buffalo and at this meeting Dr. Smith (and Miss Agnes J. 

 Quirk) presented a paper on " Hydrogen-Ion Content and Total 

 Acidit}' in Crown-Gall Tumors." '' Since 1917 Smith had asso- 

 ciated ammonia production with the pathogenicity of Bacterium 

 tuviefacieus. It may be added, furthermore, that today ammonia 

 production is believed to be the factor most common among the 

 various gall-stimulating bacteria. In this paper he again indi- 

 cated his belief that a " combined acid," (in part, ammonia) is 

 fundamental as a factor in the origin of crown gall tumors. 

 Some interesting observations on oxidation phenomena were also 

 revealed. But one theory appears to have been quite definitely 

 shaping in his mind, a theory based on his belief as to the 

 inhibitory action by acids in gall development. This would have 

 a bearing on his later explanation of immunity manifest in some 

 varieties of plants to crown gall. Much future research would be 

 done by him and other workers along these lines. 



On April 1, 1924, he had '" completed [his] abstract of Poten- 

 tiometer work on crow^n gall as far as [they had] gone — 170 

 experiments," he wrote in his diary. '" Tests are yet to be made 

 on 6 other groups of inoculated plants, making in all about 200 

 experiments." On April 9, he participated in a symposium on 

 cancer of the District of Columbia medical society. Approximately 

 one hundred and twenty doctors were present, and he spoke 

 on " Biological Aspects of Cancer." In his address before the 

 American Association for Cancer Research he announced many 



^' Jour. Cancer Research 8: 515-516, 537 f., 1924. Entries in Smith's diaries for 

 the summer of 1923 are interesting in this connection, as, for instance, that of 

 July 17. 



