May 1 6 , 1921 
Bacterial Wilt of Castor Bean 
261 
Stanford and Wolf 1 having reported successful inoculations of 
Bacterium solanacearum on the common garden balsam ( Impatiens 
balsamina L.)> we tried the Ricinus organism on these also with marked 
success, the tops wilting and the brown streaks, due to stained vascular 
bundles, showing through the translucent stems for long distances down, 
the inoculation being made near the top (PL 67, A). In such cases a 
microscopic examination showed the vascular system to be filled and 
honeycombed by the bacteria. 
Sections of Ricinus stems were cut and stained for location of the 
bacteria and disintegration of the tissues, which, corresponding to the 
slow progress of the disease in our inoculated plants, was not very 
extensive and not unlike figures already published by the senior writer 
for other plants attacked by Bacterium solanacearum. 
Since good figures of the appearance of Bacterium solanacearum on 
agar poured plates are not very numerous, some colonies are shown 
enlarged 10 times (PI. 67, B). The surface colonies on nutrient agar 
poured plates are irregularly roundish, white and shining by reflected 
light, and very fluid, so that they flow readily when placed in a vertical 
position. By transmitted light the colonies of this organism are brown¬ 
ish. By oblique light they are opalescent, the play of mother of pearl 
colors being usually very conspicuous. The organism is strongly aerobic, 
as is shown by the small buried colonies on the poured plates, feeble 
growth in the depths of stab cultures, and in various other ways already 
described. The Ricinus organism when grown on cylinders of sterile 
steamed potato produced exactly the same brown stain as Bad . solana¬ 
cearum from other plants, and its reaction in milk and litmus milk is 
also the same. 
The profound dwarfing of Ricinus plants was obtained again in 1920 
with Bacterium solanacearum plated from the wilted North Carolina 
tobacco. In 1920 fuchsias were also shown to be susceptible. 
1 Stanford, E. E., and Wolf, F. A. studies on bacterium solanacearum. In Phytopathology, 
v. 7, no. 3, p. 155-165, 1 fig. Literature cited, p. 165. 
