64 
Journal of Agricultural Research 
Vo . XXIX, No. 2 
days the cylinder will have collapsed, 
and when this collapsed tissue is tested 
with Lugol’s solution the starch will be 
found to have disappeared, showing 
that the pathogen possesses strong 
diastatic properties. An ocular dem¬ 
onstration of the ability of the pustule¬ 
forming bacterium to hydrolyze starch 
may be made by growth in plate culture 
on beef extract agar plus 0.2 per cent 
of soluble starch. If the plates are 
flooded with iodine solution after a 
week's incubation, a broad clear zone 
surrounding the colonies will indicate 
the area in which the starch has been 
destroyed by enzym activity. 
Milk. —Plain sterilized milk becomes 
separated into whey and curd, and the 
curd is slowly digested. The first evi¬ 
dence of these enzymatic activities is 
the appearance of a thin layer of clear 
whey just at the surface and below the 
pseudozoogloeal surface growth. As 
the curd forms, it slowly settles. Cul¬ 
tures three weeks old will have cleared 
with at most a small quantity of 
curd at the bottom of the culture tube. 
Litmus milk. —Lavender-colored lit¬ 
mus milk undergoes the same type 
of clearing and separation into whey 
and curd as does plain milk. Little 
or no free acid is formed, or at least 
is not formed in sufficient quantity to 
change the color of the indicator. 
Carbon metabolism. —In the pre¬ 
liminary tests on the fermentative 
ability of the soybean pustule organ¬ 
ism in which only the common sugars 
were employed, it was apparent that 
it could not by this means be separ¬ 
ated from Bacterium phaseoli. Accord¬ 
ingly, use was made in addition of 
certain rare sugars which have been 
successfully employed in distinguish¬ 
ing Bad. glycineum and Bad. sojae (11) 
and also Bad. sojae and Bad. trifoli - 
orum (7). Bouillon to which was 
added sufficient of the carbon com¬ 
pounds to make a 1 per cent solution 
was employed to follow the progressive 
changes in hydrion concentration as 
an index to fermentative activity. 
The sugar was added to cooled, sterile 
bouillon flasked in convenient quan¬ 
tities and was tubed with aseptic pre¬ 
cautions in previously sterilized test 
tubes. All were made from the same 
stock bouillon and a considerable 
number of cultures of each strain were 
made on the same day. This made 
possible the employment of several 
tubes of each strain at each reading 
at each of the consecutive intervals. 
The results of these fermentation 
tests are assembled in Tables I to IV. 
Table I .—Fermentation of various carbon compounds by the organisms from 
soybean pustule (initial Ph 7.0) 
Carbon compound 
Age of culture and Ph concentration 
3 days 
5 days 
7 days 
11 days 
13 days 
Dextrose______ 
7.0 
7 0 
7.0 
7.4 
7.6 
Saccharose._______ 
7.0 
7.0 
7.0 
7.4 
7.6 
Lactose_ 
7.0 
7.0 
7.0 
7.2 
7.4 
Maltose__ ___ 
7.0 
7.0 
7.0 
7.2 
7.4 
Glycerin_____ 
7.0 
7.0 
7.2 
7.6 
7. a 
Arabinose-__ _ . ... 
7.0 
7.0 
7.0 
7.2 
7.4 
Xylose__ . __ ___ 
7.0 
7.0 
7.2 
7.4 
7.6 
Rhamnose..... 
7.0. 
7.0 
7.2 
7.6 
7. a 
Dextrin.... .... 
7.0 
7.0 
7.0 
7.4 
7.6 
Salicin.... 
7.0 
7.0 
7.0 
7.4 
7.6 
Mannitol........ 
7.0 
7.0 
7.0 
7.6 
7. a 
Inulin............ 
7.0 
7.0 
7.2 
7.6 
7. a 
Galactose_______ 
7.0 
7.0 
7.2 
7. 4 
7. a 
Table II .—Fermentation of the same various carbon compounds by Bad. phaseoli 
from snap bean (initial Ph 7.0) 
Carbon compound 
Age of culture and Ph concentration 
3 days 
5 days 
7 days 
11 days 
13 days 
Dextrose........ 
7.0 
7.0 
7.2 
7.2 
7.4 
Saccharose......... 
7.0 
7.0 
7.2 
7.2 
7.4 
Lactose.._______ 
7.0 
7.0 
7.2 
7.6 
7.6 
Maltose. .. .. 
7.0 
7.0 
7.0 
7.2 
7.4 
Glycerin.... 
7.0 
7.0 
7.2 
7.4 
7.6 
Arabinose...... 
7.0 
7.0 
7.2 
7.4 
7.6 
Xylose......... 
7.0 
7.0 
7.2 
7.4 
7.6 
Rhamnose....... 
7.0 
7.0 
7.2 
7.4 
7.6 
Dextrin........ 
7.0 
7.0 
7.2 
7.4 
7.6 
Salicin........ 
7.0 
7.0 
7.2 
7.4 
7.6 
Mannitol..... 
7.0 
7.0 
7.2 
7.4 
7.6 
Inulin......... 
7.0 
7.0 
7.2 
7.4 
7.6 
Galactose...... 
7.0 
7.0 
7.2 
7.4 
7.6 
