108 Early Work in North America 



recognized in Europe. In 1882 Dr. Robert Hartig, in his Lehrbuch 

 der Baumkrankheiten, expressed his doubt that any plant diseases 

 are caused by bacteria. Two years later, Worthington G. Smith, 

 in his Diseases of field and garden crops, omitted all reference to 

 bacteria as a cause of disease in plants. In 1884 Dr. Anton 

 DeBary, whom Erwin F. Smith believed "unquestionably one of 

 the most learned and critical botanists the world has ever known 

 and the foremost student of cryptogamic plants," ^"^ yielded some 

 ground on this point, but refused to go further than to admit the 

 rare occurrence of such diseases. In his Vergleichende Morph- 

 ologie, he said: "As Hartig has already pointed out, bacteria 

 living in plants parasitically have scarcely been observed. The 

 generally acid reaction of plant parts may be a partial explanation 

 of this. Recently, however, Wakker has described as the yellow 

 sickness, a disease of hyacinths in Holland, in which the char- 

 acteristic symptom consists in the presence of slimy yellow bac- 

 terial masses in the vessels, etc. . . . More exact investigations upon 

 this phenomenon must be awaited." " Even as late as 1885 in his 

 Vorlesiiugen iieher Bacterien, DeBary summarized: " According to 

 the present state of our knowledge parasitic bacteria are of little 

 importance as the contagia of plant diseases. Most of the contagia 

 of the numerous infectious diseases of plants belong to other 

 animal and plant groups, principally ... to the true fungi." *^^ He 

 still awaited " successful infection experiments and the exact fol- 

 lowing out of the life history of the bacterium " in the hyacinths 

 disease. BurriU's work on pear-blight and apple-blight was men- 

 tioned, but "without other comment," Smith later pointed out, 

 " than that ' in Europe this phenomenon, so far as I know, is not 

 known, or at least has not been carefully investigated.' " "" The 

 importance of Prillieux's micrococcus was doubted by DeBary. 

 "It may turn out," he said, "to be only a saprophyte appearing 

 in consequence of other injuries." DeBary mentioned also Reinke 

 and Berthold's wet-rot of potatoes and admitted that in excep- 

 tional instances potato tubers were shown to rot when the fungus 

 Phytopbthora infestans was not present and when healthy potato 



®*The bact. dis. of plants: a critical review, Amer. Nat. 30: 626, 1896. 



''''Bad. in Rel. to Plant Dis., op. cit., 2: 10. 



•"^ The bact. dis. of plants: a critical review, op. cit., 626, n. 3. 



""^ Bact. in Rel. to Plant Dis., op. cit., 2: 10. 



