42 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



^ Reference to the literature discloses the fact that Appel ('02, 

 '02a) succeeded at an early date in isolating a bacterial organism 

 which he believed to be the cause of the potato disease in ques- 

 tion. The motive which prompted him to publish brief notes 

 (Appel, '02, '02a) on the disease, and at the same time to pro- 

 pose a name (only) for the causal organism, must be left for 

 conjecture. The fact remains that he (Appel, '03) did not pub- 

 lish a full description of either the organism or the disease until 



about a year after van Hall's ('02) dissertation was available to 

 science. 



Pethybridge and Murphy (11) must have recognized that their 

 species was very similar to van Hall's and Appel's, for in regard 

 to "B. phytophthorus" and "B. melanogenes" they state: 

 "the two organisms, if not identical, are at any rate closely al- 

 lied; and it is perhaps with some reluctance that we regard it as 

 a distinct species and suggest the name Bacillus melanogenes for 

 it. Relative to B. atrosepticus van Hall, these authors say that 

 has some points in common with their species, but differs by 

 iccurnng chiefly as isolated individuals, whereas ours is more 

 frequently found in pairs. The former is also decidedly smaller 

 m size, in spite of variations in both cases, and its action on milk 

 appears to be different from that found in our case. We were 

 unfortunately unable to obtain a copy of the detailed character 

 of B. atrosepticus [italics not in original] before our own work 



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concluded 



Harrison ('07) states that "the symptoms of the Ontario dis- 

 ease somewhat resemble those described by Appel for the 

 'Schwarzbeinigkeit,' a disease which seems rather widespread in 

 Germany." Further than this, the only comparisons made by 

 him appear m a little display chart on page 592 of his paper. 

 In this exhibit certain of the morphological and biological char- 

 acteristics of "B. phytophthorus", "B. atrosepticus ," and "B. so- 

 lanisaprus" are compared. The differences brought out are, it 

 seems to me, more apparent than real, as shown by the index 

 numbers compiled (see p. 41 ). 



As was pointed out in an earlier paragraph, Appel's name 

 iacillus phytophthorus" appears as a nomen nudum in a brief 

 iper published by him about two months previous to the ap- 

 'aranceof van Hall's "Bacillus atrosepticus." Furthermore, 

 tn Hall's dissertation embodies the earliest published descrip- 

 )n of the potato blackleg disease which is sufficiently definite 



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