BLACK ROT OF CRUCIFEROUS PLANTS. 327 
the end of 1, 2, 5, 10, and 15 minutes. Lysol in o.5 per cent solution killed in 1 minute, but 
in 0.25 per cent.solution it failed to kill in 15 minutes. Carbolic acid in 0.625 per cent solu- 
tion killed in 5 minutes, but not in 2 minutes. 
The organism is quite sensitive to the presence of sodium chloride, but not as much 
so as Bacterium phaseoli. It grew very feebly insalted gelatin (o gelatin converted into + 26 
by adding c.p. HCl). Further comparisons should be made. 
The organism is able to live in mixed cultures for a considerable time (Russell, Smith). 
In agar cultures at room-temperatures Harding states that the organism remained 
alive from 4 to 6 months. In the cool-box on potato the writer has kept it alive for a year 
(average temperature about 12° C.). 
Harding injected fresh bouillon cultures (2.5 cc. subcutaneously, 2 cc. intravenously, 
and 4 cc. subperitoneally) into rabbits with no ill effect other than a temporary loss in 
weight. 
RESUME. OF SALIENT CHARACTERS. 
PosITIVE. 
Pathogenic to Cruciferae, dissolves middle lamella, plugs vessels, forms numerous 
closed cavities in the host-plant; in cabbage causes conspicuous black stain in veins of leaf. 
Short rods with rounded ends, single or in pairs, and 
occasionally in short chains of 4 or more; sometimes 
much resembling a coccus (Coccobacillus) when crowded 
in the plant or in old cultures; sometimes slightly 
curved or irregular in shape. Long chains or non- 
septate filaments frequently occur in sugar-rich media. 
Pseudozoogloez; yellow on all media, changing to dirty 
yellow-brown in the plant and on cruciferous substrata 
(culture media); motile in newly diseased tissues and in 
young cultures, 1-flagellate; very resistant to drying 
under certain conditions. 
Surface colonies on agar or gelatin rather slow- 
growing, circular, pale yellow at first, deepening with 
age, smooth, wet-shining, flat, with distinct margin; 
buried colonies small and slow-growing; feathery X- 
shaped crystals of ammonium magnesium phosphate 
formed in beef-agar after some days; white chemical . 
halo on nutrient agar; gelatin and Loeffler’s blood 
serum liquefied slowly with brownish stain; colonies on 
gelatin feebly zoned concentrically. Rate of liquefac- 
tion depends upon the medium, it may sometimes begin 
in 24 hours in peptonized beef-broth gelatin (feebly alka- Fig. 130.* 
line to litmus) and be completed in 15 days, often slow. 
Growth in stab-cultures is usually best near the surface. Neutral or alkaline media 
produce the best growth while acids (+ 40) inhibit or retard it. Copious growth on steamed 
potato cylinders, filling the fluid in the bottom of the tube with yellow slime and convert- 
ing it into a solid alkaline mass turning brownish with age; nearly complete conversion of 
potato-starch. 
Organism blues litmus milk; it throws down casein slowly, 7.e., by a lab ferment; 
gradual digestion of casein (Smith, Harding); inverts cane-sugar (?); vitality lessened by 
long cultivation (Harding); slow production of indol in sugar-free peptonized beef-bouillon 
: 
; 
) 
. 
*Fic. 130.—Two tubes of bouillon inoculated with Bacterium campestre: Left, over chloroform (clear); right, 
check (clouded). Each tube was inoculated on Feb. 12 with a 2 mm. loop of clouded broth. Photographed Feb. 17. 
