22 Bacterial Disease of the Mango 



The long filaments are not rigid and changes of form are frequently 

 observable through curving in various directions. 



The culture was exposed to the light of a Nernst lamp during the 

 period of observation and the temperature of the room was 26 — 27° C. 



The slide was placed in the incubator at 30° C. during the night and 

 was again examined the following morning, 22 hours after the culture 

 had been made. The drop was crowded with rods of normal size ; in 

 the centre was a thick clump, cochleate in form, but all the outing 

 rods were in active motion. 



Staining reactions. 



The organism stains well with all the ordinary aniline dyes ; it stains 

 deeply with dilute aqueous solutions of methylene blue, basic fuchsin, 

 thionine and gentian violet ; and still more intensely with carbol fuchsin 

 and carbol gentian violet. The last named seems to be the best stain 

 for general purposes. 



The bacillus is not acid fast, i.e. it stains blue by the Ziehl-Neelson 

 method but is Gram-positive, and also stains by Claudius' method which 

 has recently been recommended for use in place of Gram's method (2). 



When stained by Neisser's method, the bacilli are light brown, and 

 many of them show a small black granule at each pole which is stained 

 with the acid methylene blue. The rods which showed this reaction had 

 been grown on Loffler's blood serum and incubated at 37°C. for 18 hours. 



Cultural characters. 



In all cultures made for the observation of morphological and 

 cultural characters, preliminary cultivation was practised as prescribed 

 in the chart issued by the Society of American Bacteriologists (1), 

 except that as growth was very slow at 20°C. the cultures were incubated 

 at 25°C. In describing the topography of the colonies, terms are used 

 as defined by Chester (4) and the references following names of colours 

 are to the numbers of the plates in which the corresponding colours can 

 be found in Ridgway's Colour Standards and Nomenclature (12). 



Nutrient Agar Colonies. Nutrient agar (+ 15 Fuller) was found to 

 be a suitable medium for general purposes. The most characteristic 

 colonies are developed at a temperature of 25° C. They are visible 

 after 24 hours, when they are shining white, circular bodies 1 to 1-5 nun. 

 in diameter; even at this early stage the margin of some of thorn is 

 becoming undulate; they are denser at the centre than towards the 



