318 Recognition in America 



fiionas cauipestris for publications that year."" His study of these 

 organisms was to continue for many years and in many particulars 

 he would perfect his technique. Workers then were often not 

 entirely confident of their conclusions and the correctness of their 

 methods of work. To illustrate: in 1894 he wrote of peach 

 yellows trees as " full of a virus readily communicated to other 

 trees by budding " "^ and of peach rosette as " a virus [requiring] 

 a period of some months to penetrate into all parts of a tree." ^^^ 

 But he also allied peach yellows to variegation in plants, " a 

 disease manifesting itself in stunted growth, imperfect assimi- 

 lation, hastened development, and feeble vitalit}'. Moreover, in a 

 number of variegated plants, e. g., jasmines and abutilons, this 

 condition is transmissible to healthy stocks by budding or grafting, 

 in the same way as peach yellows. The difference in these cases 

 appears to be one of degree rather than of kind." Modern research 

 has brought forth much new knowledge concerning these two 

 diseases and little peach, all three having different symptoms and 

 caused by viruses. ^^^ 



During the 1890's there was much uncertainty about the knowl- 

 edge of bacterial diseases of plants. In 1892 W. Migula, writing 

 for the Middle Java Experiment Station, had concluded that five 

 from " about twenty " ^^* bacterial plant diseases mentioned in 

 literature were "clearly established." Sorauer, Comes, Russell, 

 Ludwig, and others, then recognized that bacterial plant diseases 

 existed, but agreement among them as to how many and what dis- 

 eases had been definitely proven to be caused by bacteria was 

 lacking. In his list of diseases of established bacterial origin, 

 Russell included pear blight, Wakker's yellows of hyacinths, 

 Heinz's hyacinth rot, tuberculosis of olive, and Kramer's wet-rot 

 of potato, among several others. By 1897 Migula had increased 

 his list from five to eight maladies proved to be caused by bacteria. 

 Nevertheless, leading text-books on plant diseases continued to 



"" Centralbl. f. Bakt., op. at. ; The black rot of cabbage, U. S. Dep't of Agric. 

 Farmers' Bulletin 68, transmitted Dec. 16, 1897, published in 1898. 



^^^ Peach yellows and peach rosette, U. S. Dep't of Agric. Farmers' Bulletin 17: 10, 

 May 1894. In 1895 Smith published also Farmers' Bulletin 33, Peach growing for 

 market. 



112 pga(-j^ yellows and peach rosette, op. cit., 17. 



^^* See, L. O. Kunkel, Immunological studies on the three peach diseases, yellows, 

 rosette, and little peach, Phytopathology 26(3): 201-219, Mar. 1936. 



^^* See, Bacteria in relation to plant diseases, op. cit., 2: 12-14. The facts of this 

 paragraph are taken from the more complete discussion of this subject by Dr. Smith. 



