268 Early Studies in Bacterial Plant Diseases 



cucumber, or potato. He may have told him of other experiments. 

 There were many during that month and October.^^ He had found 

 that the germ is acid-producing, grows in alkaline media, and he 

 wanted to know whether it could change the cucumber juice from 

 an acid to an alkaline content. He was trying to explain the 

 pathological condition once the germ had entered, and he was 

 experimenting further to see whether insects were the means of 

 the germ's entering. Whatever he wrote Spalding, his former 

 professor replied: "' Now you have made a discovery. ... I ven- 

 ture to say that you have made a most important contribution to 

 plant physiology and pathology. ... I congratulate you most 

 heartily on getting hold of a new thing under the sun, as it seems 

 to me it must be." 



On November 3, Smith had planned a series of experiments to 

 determine the acid produced by the germ, its reaction on growth 

 media, and his first notation indicated a comparative study between 

 the anatomy and physiology of the cucumber plant in health and 

 the pathological changes which take place when the infective 

 action begins. In 1893 he had mapped the geographic distribution 

 of the disease. He had studied all the extrinsic aspects of the 

 malady he could think of; now he was carrying deeper his detailed 

 examination of intrinsic factors. He sketched the distribution of 

 the germ in various parts of the plant. He traced the spread of 

 the infection from organ to organ. His ultimate aim seems to 

 have been to examine the aspect of acidity under conditions of 

 disease, and to test the organism's growth on various culture 

 media, as well as in the plant, was part of this aim. 



In September he had begun to distinguish between a primary 

 and a secondary wilt. By October his broth cultures had been 

 increased from four to nine. He found that the germ could live 

 on meat extract peptone agar twenty days. Later he discovered 

 that, under favorable conditions, the organism would live and 

 multiply for almost four months with the use of suitable media. 

 He next experimented with acidified broth cultures. At the same 

 time he maintained some thermal death point experiments. He 

 uncovered facts of especial interest while testing the germ's sensi- 

 tivity to organic acids — acetic, malic, citric, oxalic, and tartaric. 



'■^ Bacteria in relation to plant diseases, op. cit., 2: 219-233. 



