152 



BACTERIAL DISEASES OF PLANTS 



FIG. 91. ,4, B. Surface and buried colonies of Bacterium campestre (isolated 

 from D. C. rape) at end of 13 days on + 14 beef-peptone agar plates. Four crystals 

 are present, 3 in colonies. A' is a buried colony coming to the surface. Photo- 

 graphed by transmitted oblique light February 13, 1919. X 10. 



