66 
Journal of Agricultural Research 
Vol XXIX, No. 2 
gm.; potassium chloride, 0.5 gm.; fer¬ 
rous sulphate, 0.01 gm.; agar, 20 gm. 
Digestion of casein. —Evidence in 
addition to that obtained in milk cul¬ 
tures of the ability of the organism 
from soybeans and Bad. phaseoli to 
digest casein was obtained by adding 
1 per cent casein to the stock agar 
in poured plate cultures. After a 
week’s incubation wide halos, in which 
the casein was entirely dissolved, had 
formed around the colonies, thus 
demonstrating the ability of these or¬ 
ganisms to form erepsin. 
Digestion of asparagin. —Stock 
agar plus 1 per cent of asparagin was 
used in these tests. The indicator 
consisted of a sufficient quantity of 4 
per cent solution of rosolic acid, and 
sufficient NaOH was added to give the 
medium a decided orange color and a 
reaction of about P H 6.0. In poured 
plate cultures incubated for about 10 
days, the orange color gave way to a 
beautiful brilliant red. This change 
begins with a halo around each colony 
and comes to involve the entire plate. 
The change in color is due to the libera¬ 
tion of ammonia in the decomposition 
of asparagin as a result of the activity 
of the enzym amidase. 
Digestion of serum. —Blood serum 
added to stock agar in poured plate 
cultures was planted with the several 
strains of bacteria. This medium in 
cultures 7 to 10 days old serves as a 
satisfactory means of demonstrating 
the ability of these organisms to 
liquefy blood serum. 
Liquefaction of gelatin. —Growth 
in stab cultures on gelatin is slow, but 
within a period of two weeks the gela¬ 
tin to a depth of about a centimeter 
will have become liquefied. Liquefac¬ 
tion begins as an infundibuliform area. 
Reduction of nitrates. —Nitrate 
broth consisting of 1 per cent peptone, 
0.3 per cent beef extract, and 0.1 per 
cent potassium nitrate supports abun¬ 
dant growth. No indication of ni¬ 
trites was secured when the tests at 
appropriate intervals were made with 
sulphanilic-acid solution or with naph- 
thylamine acetate solution. 
Indol production. —No indication 
of indol was secured by either the 
Salkowski, Vanilin, or Ehrlich test. 
Thermal death-point. —In deter¬ 
mining the thermal death-point, tubes 
of bouillon P H 6.6 were inoculated from 
vigorously growing bouillon cultures 
and subjected for 10 minutes in the 
usual manner to various trial tempera¬ 
tures. As a result of these tests, and 
under these conditions, the thermal 
death-point was found to be 50°C. 
RESISTANCE TO DESICCATION 
An inoculum of the soybean organ¬ 
ism from cultures on potato cylinders 
48 hours old was suspended in sterile 
water and drops of this suspension were 
transferred to sterile cover glasses kept 
in sterile Petri dishes. After desicca¬ 
tion at laboratory temperatures certain 
of these cover glasses were, at definite 
intervals, inserted into tubes of nutrient 
broth. Growth appeared after 18 
days’ desiccation, hence the organism 
may be regarded as very resistant to 
drying. 
PATHOGENICITY 
Only a few pathogenicity trials were 
made. Pure cultures from young 
transfers on potato agar were sus¬ 
pended in sterile water, and this bac¬ 
terial suspension was applied with an 
atomizer. When inoculations were 
made late in the afternoon and the 
plants were covered until the following 
morning with bell jars, a large number 
of centers of infection developed. 
The first evidence of infection was 
noted within four to six days, appear¬ 
ing as tiny elevations. Within a week 
later these had developed into typical 
lesions. From these the original organ¬ 
ism was reisolated in trials with several 
of the strains. Plants in all stages of 
development from those with the first 
pair of true leaves to plants with mature 
foliage are subject to infection with 
pure cultures. Both garden beans and 
Lima beans have been inoculated in the 
same manner, and in some cases with a 
portion of the same inoculum; but no 
evidences of infection have been ob¬ 
served on these inoculated plants. 
When Baderium phaseoli was em¬ 
ployed as an inoculum on Phaseolus 
and on soybeans, an abundance of 
typical bean-blight lesions developed 
upon both the foliage and pods of 
Lima bean and of garden bean but no 
evidence of pathogenicity to soy¬ 
beans was noted. 
Miss Hedges has reported (4, 5) the 
production of infection on soybeans 
and several varieties of garden beans 
following inoculation with pure cultures 
of the soybean pustule organism. The 
spots on Phaseolus were like those 
caused by Bad. phaseoli with no evi¬ 
dence of pustule formation such as oc¬ 
curs on soybean. She furthermore has 
found that Bad. phaseoli from Phaseo¬ 
lus is only weakly pathogenic to soy¬ 
bean. 
The differences in regard to cross 
inoculation are no doubt due to 
conditions of inoculation. This opin- 
