122 The South African Mulberry Blight 



Nutrient gelatine stab. There is no liquefaction; the best growth is 

 at the top of the gelatine; on the depth of the medium there is no 

 growth, even along the needle track. The medium is not stained and 

 there is no odour. 



Potato. On this medium the growth is thin, spreading, glistening, 

 white to dirty white. The medium is slightly greyed; there is hardly 

 any action on the starch. 



Nutrient broth (+ 15) rapidly becomes turbid; a pellicle is formed 

 which breaks up and falls to the bottom of the tube, forming a thick, 

 white, flocculent sediment. 



Litmus milk becomes blue rather rapidly though not so quickly as 

 with B. cani'pestre. There was no coagulation or other change during 

 the two months the tubes were under observation. The reaction is 

 continuously alkaline. 



Colitis solution. No growth. 



Fermentation tubes. There were no gas formation and no clouding 

 of the closed arm in beef broth containing 2 % of the following carbo- 

 hydrates : dextrose, saccharose, lactose, maltose, glycerine and mannite. 



Indol. No reaction for indol except a doubtful one in a single tube. 



Nitrates. There was no reduction of nitrates in nutrient broth 

 containing potassium nitrate. 



Sodium chloride. The organism grew vigorously in nutrient broth 

 containing up to 6*5% sodium chloride; feebly in broth containing 

 6-5 % to 7-5 % . Tubes containing higher percentages remained clear. 



Chloroform. The organism can grow vigorously and for a long time 

 in broth over chloroform ; but in a number of cases when not copiously 

 inoculated it failed to do so. 



Temperature. The organism grows well at 25° C. and also at 20° C. 

 It was killed by 10 minutes' exposure in thin glass tubes to a tempera- 

 ture of 50° C. Smith gives a slightly higher death point, 51|° C. Tubes 

 exposed to a temperature of 48° C. rapidly became turbid. 



Desiccation. Cultures were obtained from leaves which had been 

 drying in the air of the laboratory for 12 months. The resistance of 

 the organism to drying on cover glasses was not tested. 



Sunlight. Thinly sown plates were exposed to bright sunlight 

 bottom upwards on ice. The rods were all killed in those exposed for 

 30 minutes; there was considerable reduction in the number of colonics 

 in those exposed for 15 minutes, and still more after 25 minutes. The 

 exact percentage was not estimated. 



