BIvACKIvliG. 311 



solanisaprus."'''' In this account he describes a chsease of the 

 stem and tuber of the Irish potato which he had under observa- 

 tion in different provinces of Canada at least as early as 1900. 

 He very carefully studied and described in considerable detail 

 the organism responsible for the disease, which he called 

 Bacillus solanisapnis, n. sp., differing in some respects from the 

 description of B. solaiiicola Delacroix and B. phytophthorus, 

 the latter of which is given by Dr. Appel as the cause of the 

 Schzuartzbeinigkeit in Germany.t Professor Harrison found 

 his organism to be pathogenic on various varieties of potatoes, 

 and also demonstrated its ability to produce soft-rots on a con- 

 siderable number of unrelated vegetables. 



It is not the province of this article to discuss the relation- 

 ship of the bacteria associated with blackleg in Maine with those 

 already described as a cause of disease of the potato in America 

 and elsewhere, or to take up in detail the morphological, cul- 

 tural, physical and biochemical features of the organisms. \Mien 

 the studies now in progress are completed these questions will 

 be discussed in detail but a general statement at this time may 

 be of service. 



Pathogens from two dift'erent sources have been secured 

 which are not identical in all respects in cultural characters, but 

 it is doubtful if these differences are of sufficient amount to con- 

 stitute separate species. One of these agrees in most respects, 

 as far as studied, with the published description of B. solaii- 

 isaprus, except in its ability to ferment certain carbohydrates 

 which Harrison says the latter does not ferment. Ordinarily 

 this would be considered sufficient to constitute a separate 

 species. On the other hand, extended study of the fermentation 

 of dextrose, lactose, and saccharose by the closely related organ- 

 isms causing soft-rots of various vegetables indicates that with 

 germs of this class fermentation of the carbohydrates mentioned 

 is not strong and is very variable. Hence with this group it is a 

 questionable character upon which to erect a species. t More- 



* Harrison, F. C, Central, f. Bakt. II Abt. XVII, p. 34 ct scq (1906). 



tAppcl, Dr. Otto, Arb. K. Gsndhtsamt., Biol. Abt., 3 (1903), No. 

 4, pp. 3^H-43^- 



t Harding, H. A. and Morse, W. J. The Bacterial Soft Rots of Cer- 

 tain Vegetables. Technical Bulletin No. 11, Part i. N. Y. Expt. Station 

 (1909). 



