602 
Journal of Agric ultural Research 
Vol. XXVIII, No. 6 
CONCENTRATION OF THE INHIBITORY SUBSTANCE 
An active filtrate was added to broth cultures of young cabbage-rot bacillus 
in dilutions starting with 1 to 10 and progressing by dilutions of 10 up through 
12 dilutions, or to a final dilution of 1 to 1,000,000,000,000. The tubes of broth 
contained 9 cc. of broth. To the first tube was added 1 cc. of filtrate making 
a l-to-10 dilution. Using the same pipette, 1 cc. was taken from this tube to 
the second, and so on !through the set. All of these tubes showed inhibition 
through a dilution of 1 to 100,000,000,000. 
After a period of several months, the above experiment was repeated, using 
higher dilutions. The dilutions this time were run up by dilutions of 10 to a final 
dilution of 1 to 1,000,000,000,009,000,000. The filtrate still showed inhibition 
at a dilution of 1 to 100,000,000,000,000,000. The last dilution failed to show 
any inhibition. 
The dilution in which the inhibitory substance is active is extremely high, far 
higher than could be induced through any toxic material produced by the or¬ 
ganism. There is but little doubt that the material isolated is comparable to 
inhibitory substances obtained from animal sources. 
The organism upon which the inhibitory substance was active proved upon 
identification to belong to the fluorescent group rather than Bacillus carotovorus . * * * * 5 
However, this organism does decompose cabbage. Experiments to determine its 
decomposing power showed a slow rotting, several weeks being required for 
complete liquefaction of the cabbage. 
Filtrates made from the pure culture never showed the inhibitory substance 
nor did the culture of Bacillus carotovorus. This proves that the inhibitory 
substance must have come from the cabbage. Filtrates from normal cabbage 
failed to show the inhibitory substance, which indicates an association of the 
inhibiting substance with the disease-producing organism. This is similar to 
conditions in the intestinal tract of animals as demonstrated by d’H^relle. 6 
CONCLUSIONS 
An inhibitory substance was isolated from a rotten cabbage which was active 
on an organism obtained from the same cabbage. 
The inhibitory substance became active against other soft rot-producing 
organisms but this activity was lost by further transplanting. 
The inhibitory substance was not destroyed at 56° C. for 20 minutes, but was 
destroyed at 63° for 30 minutes, showing a sensitiveness to heat comparable to 
microorganisms and lytic substances isolated from animal sources. 
The inhibitory substance was present in extremely large amounts, as indicated 
by its activity in high dilution. It was therefore probably not a toxic product 
of the organism. 
Lytic and inhibitory substances are probably found in plants as in animals. 
It is hoped that this brief preliminary report will open up this field and show 
the extent of lytic and inhibitory substances in the plant world. 
6 The organism is approximately the same size and shape as Bacillus carotovorus. It occurs singly and is 
sluggishly motile; Gram-negative, no gas produced in dextrose, lactose, or saccharose broth. Plain broth 
becomes decidedly turbid in 24 hours with a slight pellicle appearing in six to seven days, at which time a 
yellowish green coloration appears near the surfaoe. Tbe agar slant shows an abundant white opaque 
growth with no discoloration of the medium. Gelatin is liquefied. 
6 d’H^relle, F., the bacteriophage, IT3 role in immunity. ... tr. by G. H. Smith. 287 p., illus 
Baltimore. 1922. 
