Last Work. Final Honors 591 



flowers." -^ He photographed one, and added to his memorandum: 

 " 14 of these yellow flowers and 18 subtending green bracts. Some 

 small tumors in the vicinity but most in stem under the flower 

 head.'" His potentiometer tests of sugar beet crown galls had 

 yielded results " consistent with all that have preceded. The 

 tumors, even these relatively young ones none of which show any 

 necroses, [were] 2-4/10 pH more alkalme than the normal tissues 

 of the sound sides of same beets." Most of the month had been 

 given, therefore, to testing the sunflower crown galls for pH and 

 total titratable acidity, and the work had brought forth a discovery 

 of sterile ray flowers in the middle of sunflower heads. The full 

 significance of thfS was not realized until the following years, 

 1924 and 1925. But, during 1923, he did not forget what he had 

 observed, and later, when we consider his work of these years, 

 we shall find this discovery supplying the basis for months of 

 research. 



During August of that year, Dr. and Mrs. Smith attended a 

 reunion of old residents of Gilberts Mills, New York, and then 

 took a journey into Canada and the New England states. 



W^hen he returned to his laboratory, his attention was at once 

 called to the " good grov.-th " some Begonia plants had made 

 during the passed six weeks. In April he had begun experiments, 

 evidently injuring leaves in one way or another to study any 

 resulting proliferations. But he was disturbed to find the varia- 

 tions in proliferation graded from " very slight " to abundant, 

 and so he started some new experiments to restudy the results. 

 At some time either that year or early in the next, nematode galls 

 due to Heterodera radidcola were found on the crowns of a tall- 

 growing begonia. The same cultures of Bacterium tumefaciens 

 which produced tumors in sunflowers, sugar beets, and Ricinus 

 plants failed to produce tumors on Begonia lucerna, although 

 the experiments were three times repeated. Dr. Smith and Miss 

 Quirk, therefore, began a series of potentiometer studies on this 

 plant. Begonia phyllomaniaca which had been the subject of the 

 spring to autumn 1923 experiments, and other begonias.^" Even- 

 tually the studies were extended to onions, garlic, banana, sugar 

 cane, and many other plants to determine not only their acidity 



"' Dian*, 1923, July 23; quotation concerning sugar beet crown palls, July 2. 

 '" A " B. P. I. Hybrid Begonia " was another variety especially studied. 



