484 Second European Journey 



discover competing saprophytes which when sown on infected 

 soils will overcome and render harmless certain of the bacterial 

 parasites present in them. We have some evidence that nature 

 does this, and man working toward a definite end should be able 

 to improve on nature." 



Smith in 1914 placed conjfidence in the " rapidly increasing 

 knowledge of the biological peculiarities of the parasites causing 

 these diseases, and of the ways in which they are disseminated. . -. ." 

 His hope for the future was in wider application of control- 

 methods already found, and in the discovery of new rules experi- 

 mentally worked out by plant pathologists and based on " indi- 

 vidual peculiarities of the parasites." That this hope was not 

 yielded during his lifetime is shown by an utterance formally 

 made in 1926 near the close of his life: " We know as yet," 

 he said,^° " very little about bacterial symbiosis and antagonism 

 in relation to disease, but beyond doubt there is a great deal to 

 learn." 



In the second volume, indeed in all three volumes, of Bacteria 

 in Relation to Plant Diseases, he suggested to plant scientists 

 some " wholly unworked " fields for future investigation. This 

 he did in many of his most important scientific writings. If the 

 field was not wholly unworked, he suggested subjects which he 

 confidently believed would yield more valuable results and subjects 

 which he was sure should be studied and investigated further. 

 Among wholly unworked fields, he suggested plant studies in 

 acquired resistance to, and immunity from, disease.^^ 



Originating valuable disease-resistant strains of plants by selec- 

 tion or hybridization, and this included the newer resources being 

 discovered by research in genetics, represented a type of future 

 investigation v/hich he was sure would be still more useful in 

 solving problems. Much of his writing had important bearings 

 on animal and medical pathology, yet were based on results exclu- 

 sively from the study of plants. It took scholarship of high order 

 to answer such a question as, "Are any bacteria known to cause 

 disease in both plants and animals?" and adduce his answer 

 from available experimental data the world over resulting from 

 inoculations of plant parasites into animals and animal parasites 



^^ Fifty years of pathology, op. cit., 40. 



^^ Bacteria in relation to plant diseases, op. cit., 2: 93-96. 



