PLATE 67 
A. —Two stems of the common garden balsam (Impatiens balsamina), showing 
internal brown striping due to the Ricinus wilt organism. The plants were inoculated 
June 26, 1918, and the photograph was made July 11. The bacteria were extremely 
abundant in the vessels of these stems. Surface unbroken. 
B. —Agar poured-plate colonies of Ricinus wilt orgnism, photographed vertically 
and introduced to show fluid nature of the colonies and also the strongly aerobic nature 
of the organism, as may be seen by the small size of the buried colonies as con¬ 
trasted with the two surface colonies. The colonies flow when tilted, are smooth 
and glistening on the surface, white by reflected light, pale brown by direct transmitted 
light, and opalescent by oblique light. Plate 4 days old at 26° C. It makes no 
difference in fluidity of the colonies whether Witte's peptone is used in the agar or 
Difco peptone. The opalescence by oblique light is usually very striking. Photo¬ 
graphed June 17, 1918. X 10. 
