34 



Bacterial Disease of the Mango 



It will be noticed from this summary, that the organism does not 

 grow anaerobically in the presence of glycerine and lactose, and only 

 feebly in the presence of galactose and dextrin. 



Hydrogen sulphide. Tubes of peptone lead solution (8, p. 186) were 

 prepared in order to test for the presence of H 2 S. Cultures in this 

 medium were kept under observation for sixteen days, but there was no 

 formation of hydrogen sulphide; the precipitate was not blackened. 

 At the end of sixteen days the cultures were discarded. 



Toleration of NaCl. The bacillus can grow in media containing 

 comparatively large percentages of sodium chloride. A number of 

 tubes containing various percentages of NaCl (from -5 % to 10 %) in 

 + 15 nutrient broth were inoculated from a young culture and incubated 

 at 30° C. Tubes containing less than 4 % NaCl were clouded in 18 

 hours, while those containing from 4 % to 8-25 % were clouded in 48 

 hours. In tubes containing 9 % and over there was no growth ; in 

 the 8-5 % and the 8-75 % solution the clouding was so slight as to be 

 barely noticeable, but a microscopic examination showed that the 

 organism had multiplied considerably. The abnormal forms found in 

 this medium have been described elsewhere. 



Reaction of medium. The organism is not particularly sensitive to 

 the reaction of the medium in which it is grown. The optimum is about 

 + 17 of Fuller's scale, but there is very little variation in the rapidity 

 of growth in media of reactions varying from +14 to + 23 Fuller. 

 During an experiment undertaken to find the optimum reaction, broth 

 tubes having these reactions clouded in six hours at 30° C. ; those with 

 a reaction of + 2 to + 14 and from + 24 to + 27 Fuller clouded in 

 seven hours; those with reactions from + 28 to + 30 and from + 10 to 

 + 1 in eight hours. In tubes containing more alkaline broth growth 



