210 Studies in Bacteriosis 



parative experiments were made. The table given below shows how 

 closely the two organisms agree in their physiological behaviour ; certain 

 morphological ami cultural characters, however, point to differences 

 which although they may not be specific differences at least serve to 

 differentiate the two organisms as separate strains; these characters 

 were constantly observed even after the two had been cultivated 

 simultaneously through a succession of transfers during two months 

 over which the experiments were made. Barker and Groves organism 

 does not grow so rapidly as the mushroom organism, it forms long thread- 

 like involution-forms on the second day at 25° C. which the latter does 

 not, it has its optimum for growth at 18° C. whereas the latter grows 

 best at 25° C, the thermal death point which may be conceived to be one 

 of the most secure of criteria is two degrees lower than that of the mush- 

 room organism. Finally, a marked difference is found in the viscosity 

 of liquid cultures: Barker's organism produces in bouillon and 

 Uschinsky's solution^ a gelatinous deposit in old cultures, w^hereas the 

 whole solution becomes mucus-like in threo-day-old cultures of the 

 mushroom organism. 



The organism described by Miss Doidge(2) as the cause of Pear- 

 blossom Blight in S. Africa and named Baderinni nectarovhihnn has 

 many characters in common with the mushroom disease organism. It 

 differs only in the length and number of its fiagella, both of which may 

 be merely cultural variations, in the possession of a capsule and in its 

 inability to liquefy gelatine. This last is a very striking character, but 

 we have not as yet sufficient evidence to be able to judge in how far it 

 is a constant one. The work of Morse (5) has shown that in one case, 

 namely that of Bacillus solanisaprvs, the power to liquefy gelatine co\ild 

 be developed under suitable cultural conditions and that this organism 

 was really a strain of a vigorous liquefier, Bacillus atrosepiciis. The 

 identity of Bacterium nectar ofhilum with the organism described in this 

 paper is then not beyond the region of possibility, and the hypothesis 

 that Pear-blossom Blight and the Mushroom Disease may be produced 

 by one and the same organism may yet prove to have some foundation 

 in fact. Barker's organism was used in inoculation of mushrooms and 

 found to have no effect upon them, but this has little significance since 

 the organism had been in artificial culture for a considerable time and 



1 Harker and Grove's organism was found by Miss Doidge (2, p. 58) to give no growtli 

 in Uschinsky's solution. This was not my experience. Slight growth resulted and the 

 liquid became strongly alkaline, then bleuchetl at the bottom and a gelatinous precipitate 

 was formed. 



