THE ANGULAR LEAF-SPOT OF COTTON I TECHNIC 



333 



be removed and the surface bacteria restored to a growing con- 

 dition), then the spot is crushed thoroughly in bouillon and, 

 after a half-hour's delay with more or less shaking to diffuse 

 the bacteria, the plates may be poured. 



Determine 



FOR THE ORGANISM. Morphology. Size in microns, form 

 (stain with Ziehl's carbol fuchsin or amyl Gram), aggregation 

 of elements, motility (margin of a hanging drop), number and 



FIG. 255. Accidental inoculation of Bacterium malvacearum on cotton 

 bolls by spraying, July 7, 1915. Photographed August 2. These are secondary 

 infections by means of the gardener's hose and are approximately 2 and 3 weeks 

 old. 



location of flagella (van Ermengem's silver-nitrate stain), 

 absence of endospores (heat, stains), presence or absence of 

 capsule (Ribbert's capsule stain), occurrence of involution forms, 

 reaction to Gram's stain, acid-fast stain. 



Cultural Characters. On nutrient agar, on gelatin ( + 10), 

 on Loffler's solidified blood serum, on steamed potato, in 



