May 10, 1924 
Isolation of an Inhibitory Substance from Plants 
601 
Table IV.— The effect of the cabbage-rot filtrate after repeated invigorations a 
Culture 
Control 
Amount of filtrate added 
1 drop 
2 drops 
2 cc. 
Cabbage-rot organism...... 
- 
++++ 
++++ 
_ 
H 1 i_~j_ 
++++ 
-H—!—h 
++++ 
++++ 
++++ 
++++ 
Dol________ 
.Bacillus spieckermani.- ____ 
do..: _____ 
Bacillus carotovorus. ___ 
Do______ 
Potato-rot bacillus______ 
Do______ 
a The following symbols are used in the tables: —, very strong turbidity; ±, slightly less turbidity; 
-f, cloudy; -f-K less cloudy; 4-++, nearly clear; ++++, clear. 
Table V. — The effect of heating the filtrate at 56° C. for SO minutes a 
Culture 
Control 
Amount of filtrate added 
1 drop [ 2 drops 
2 cc. 
Cabbage-rot organism_ _ 
- 
+ ++ 
± 1 * 
++++ 
it 
Do............ 
« The following symbols are used in the tables: —, very strong turbidity; ±, slightly less turbidity; 
-h cloudy; ++, less cloudy; -+-++, nearly clear; ++++. clear. 
Table VI. — The effect of heating the filtrate at 63° C . for SO minutes a 
Culture 
Control 
Amount of filtrate added 
1 drop 
2 drops 
2 cc. 
Cabbage-rot organism, unheated filtrate.._ 
— 
++++ 
++++ 
++++ 
++++ 
++++ 
++++ 
Dol. 1 ... 
Cabbage-rot, heated filtrate..... 
Dol_ 1 ... 
« The following symbols are used in the tables: —, very strong turbidity; ±, slightly less turbidity; 
+, cloudy; ++, less cloudy; +++» nearly clear; +-f++, clear. 
where a large amount of filtrate was added, but refused to inhibit the potato-rot 
bacillus. A filtrate made two weeks later from these tubes failed to inhibit B. 
spieckermani and B. carotovorus but was still very active against the cabbage-rot 
bacillus. 
RESISTANCE OF THE INHIBITORY SUBSTANCE TO HEAT 
An active filtrate was heated to 56° C. for 20 minutes and then added as 
usual to the cabbage-rot bacillus. 
The heating at 56° C. for 20 minutes decreases the activity of the inhibitory 
substance but it was still active enough to show partial inhibition in one case. 
A second active filtrate was now heated to 63° C. for 30 minutes and added 
as usual to young organisms in broth. 
This temperature caused a complete destruction of the inhibitory substance 
as shown in the above table. This checks very favorably with previous work 
by others working on similar substances isolated from animal sources. 
