600 
Journal of Agricultural Research 
Vol. XXVIII, No. & 
sterile filtrate were then added to these tubes, as shown in Table I. The results 
were obtained in 48 hours. The tubes of the cabbage-rot organisms were now 
filtered as before and the filtrate again added to fresh broth cultures, with the 
results shown in Table II. 
As Tables I, II, and III indicate, the second transfer shows a marked improve¬ 
ment in the inhibition of the organism and the third transfer shows an even more 
decided improvement over the second. In other words, a marked development 
of the inhibitory substance resulted from invigoration by transplanting. 
Table II.— The effect of the cabbage-rot organism after one invigoration 
Culture 
Control 
Amount of filtrate added 
1 drop 
2 drops 
2 cc. 
B. carotovorus ......... 
Do......... 
_ 
_ 
_ 
_ 
Cabbage-rot organism______ 
_ 
+ 
4- 
+ 
Do.......... 
_ 
4- 
4- 
a The following symbols are used in the tables: —, very strong turbidity; ±, slightly less turbidity; 
+, cloudy; 4-+, less cloudy; 4--H-, nearly clear; ++++, clear. 
In the same manner a third set was prepared with the following results (Table* 
III): 
Table III.— The effect of the cabbage-rot filtrate after two invigorations a 
Culture 
Control 
Amount of filtrate added 
1 drop 
2 drops 
2 CC. 
Cabbage-rot organism.......... 
-j- 
++ 
++++ 
Do.. . . . . . . 
_ 
+++4- 
++ 
i 
++++ 
a The following symbols are used in the tables: —, very strong turbidity; ±, slightly less turbidity; 
+, cloudy; less cloudy; +++, nearly clear; ++++, clear. 
This substance is called an inhibitory substance because the tubes containing, 
the filtrate remained clear for 48 hours and then slowly showed growth. The 
control tubes, on the other hand, were turbid in 24 hours. In no case was any 
evidence of lysis apparent, all the tubes showing only a retardation of growth for 
at least 48 hours. 
The type of growth appearing in the tubes containing the filtrate was very 
interesting. The tubes after 48 hours would show a thin pellicle on the surface' 
with a clear liquid beneath and no sediment. Upon agitation, this pellicle would 
break into granules, which would sink to the bottom of the tube. Upon shaking 
the tubes, the granules would break up and a persistent turbidity would result.. 
The control tubes, on the other hand, would show a persistent turbidity in 24 
hours without pellicle or sediment. The filtrate apparently induced this change 
of growth to take place. 
Unpublished work by one of the authors (Mallmann) showed exactly the same 
occurrence in broth with Bacillus coli where an inhibitory substance of like 
nature was added. Plates from tubes of cabbage-rot organism showed only the 
typical normal colonies. These differ from the plates of B. coli where two types, 
were found, a normal colony and a so-called “rough” colony, as shown by 
Bergstrand. 4 
After repeated transfers, the inhibitory substance adapted itself to some extent 
to other related organisms. It inhibited Bacillus spieckermani and B. carotovorus 
4 Bergstrand, II. on the variations of bacterium coli. Jout. Bad. 8:178-192, Ulus. 1928. 
