SCHIZOMYCETES. BACTERIA 113 



sweet corn have been successful. The organism is probably spread 

 by many mechanical agencies, and also distributed clinging to the 

 seed. 



The organism, morphology and reactions. The rods are short, 

 almost ovoidal in form, ordinarily 1.3-1.6 X ./-.8 /JL. On agar 

 the colonies are more or less circular, becoming lobulated at the 

 margins. With age the surface is granular. The color changes 

 from yellowish white to bright yellow. Gelatin is not liquefied. A 



FIG. 27. LONGITUDINAL SECTION OF STALK OF SWEET CORN, 

 SHOWING A DISEASED BUNDLE. (Photograph by F. C. Stewart) 



vigorous growth is produced on steamed potato, which in a week 

 is iridescent. The potato turns brown in time. 



In bouillon a turbidity is produced, and gradually a yellowish- 

 white precipitate is formed. Yellow, surface-colony globules appear. 

 In Uschinsky's solution there is a vigorous growth, litmus milk is 

 slowly decolorized, and there is no coagulation. Gas is not pro- 

 duced, and the organism is aerobic and facultative anaerobic. 



Control measures. There is great difference in the susceptibility 

 of varieties of sweet corn, and this may be made use of where 

 necessary. Only sound seed from uninfested regions should be 

 employed. A rotation of crops is also an important precautionary 

 measure. 



