208 



BACTERIA IN RELATION TO PLANT DISEASES. 



Mr. Tryon's name, or some portion of it, had I at that time had any means of knowing 

 what he meant by it. This I did not know, and do not yet know. His organism certainly 

 can not be like three very different organisms. It would appear that Mr. Tryon had written 

 a considerable manuscript on this disease and had submitted it to the Department of Agri- 

 culture of Queensland, but that unfortunately they allowed it to remain unpublished. He 

 now^makes citations from this unpublished paper, but these are not sufficient to clear away 

 the uncertainties. For all we know from anything he has published, this Australian disease 

 may be due to Bacillus'phytophthorus, or to some undescribed species. Mr. Tryon has never 

 published a proper (exact) description either of the disease or of the organism causing it. 



Certain statements of his do, indeed, make the 

 reader think of the brown rot, but there are others 

 which certainly can not be applied to Bact. sola- 

 nacearum, e. g., the "sticky, tenacious" slime which 

 is said to choke up the vessels; the "froth-like" 

 viscid exudate from the eyes of the tuber; the 

 "foetid odor," the opening of the lenticels; the 

 gradual decay of the stems from the base upward ; 

 the frequent destruction of the organism by the 

 temperature of the Queensland summers, etc. Mr. 

 Tryon is either describing mixed infections, or else 

 a different disease. Why not "Schwarzbeinigkeit" 

 due to Bacillus phytophthorus? 



We shall never know the specific cause of this 

 Australian potato disease until some bacteriologist 

 takes hold of the problem, isolates and describes 

 the organism in ways recognized as proper, and 

 demonstrates his ability to reproduce the disease 

 with one particular organism by means of pure- 

 culture inoculations. 



A few words as to Mr. Tryon's name. In my 

 judgment the name Bacillus vascularum solani is 

 unusable because it can not be attached, by means 

 of anything he has yet published, to any particular 

 organism. It is a trinomial, it was published with- 

 out description, without isolation of the organism 

 in pure culture, without proof that the bacteria 

 actually under observation and named by him had anything to do with the disease, with- 

 out proof that the disease itself was actually due to bacteria, and finally without careful 

 description of the disease, e. g., such descriptions as would have enabled anyone to identify 

 it with the North American disease. His name, therefore, for reasons sufficiently set forth 

 in volume I of this monograph, can be regarded only as a nomen nudum. 



Professor McAlpine, of Melbourne, has sent me a photograph (fig. 114) of a potato- 

 tuber decaying at the eyes, this disease being known in Australia as "sore eye" and "spewey 

 eye. " This disease is associated with bacteria and probably due thereto. Some years it 

 causes great losses, it is said. Perhaps it is the disease observed by Tryon. Living material 

 sent to me was too badly decayed when received to make anything out of it. It appeared 

 to be a brown bacterial rot (only a little Fusarium was present), and the vicinity of the 

 vascular ring was stained darker than any other part. 



*FlG. 114. Potato tuber, showing the bacterial "sore eye" or "spewey eye" of Australia. From a photograph 

 sent by Prof. D. McAlpine, of Melbourne. This is perhaps Tryon's disease. There is a slimy ooze from the eyes and 

 the earth usually sticks to them. 



Fig. 114.* 



