THE ANGULAR LEAF-SPOT OF COTTON: 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 



mw 



Fig. 255. — Accidental inoculation of Bacterium vialvac^arurn 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 



