268 
Journal of Agricultural Research 
Vol. XXVIII, No. 
Table II .—Toleration of organic acids 
Citric acid 
Malic acid 
Tartaric acid 
Fuller’s 
scale 
Ph 
Growth 
Fuller’s 
scale 
Ph 
Growth 
Fuller’s 
scale 
Ph 
Growth 
+17 
Prompt heavy 
+17 
Prompt heavy 
+17 
Prompt heavy 
+28 
clouding. 
clouding. 
clouding. 
5.7 
Delayed heavy 
+25 
5.8 
Delayed heavy 
+24 
5.7 
Delayed heavy 
+33 
5.4 
clouding. 
No growth. 
+33 
5.2 
clouding. 
No growth. 
+29 
5.2 
clouding. 
No growth. 
Indol production. —No indol is produced in 10 days’ growth either in Dun¬ 
ham’s solution or in Uschinsky’s solution to which 2 per cent Difco peptone 
was added. Tests were made with sodium nitrite and sulphuric acid. Cul¬ 
tures of Bacillus coli tested at the same tfme gave a good pink reaction. 
Effect of dessication. —The organism is rather resistant to drying. Small 
drops from 24-hour beef bouillon cultures were spread on sterile cover slips 
in sterile Petri dishes and kept in the dark. Most of the covers when dropped 
into tubes of bouillon after 9 days’ drying caused clouding, many clouded the 
bouillon after 12 days’ drying, and some were able to cloud the bouillon after 
20 days’ drying. Plates were poured from these last which gave pure cultures 
of the right organism. 
Thermal relations. —The organism grows at temperatures from 1° to 30° C. 
in beef bouillon +12, Ph 7.1, with an optimum growth at 25°. At 1° clouding 
began on the sixth day and gradually (within three weeks) became heavy and 
green fluorescent with a pellicle. At 30° growth was very weak, even after 
three weeks, and without either pellicle or green color. Fresh transfers to 
bouillon kept at 34°, 35°, and 37° for eight days, when removed to room tem¬ 
peratures (23° to 25°) failed to cloud although held for two weeks. 
The thermal death point is 50° C. when test-tube cultures in beef bouillon 
(P H 6.8 to 7.2) are exposed in a water bath for 10 minutes (tube diameter 16 
mm.) 
Effect of Freezing. —Transfers were made to beef bouillon (+12, P H 6.7) from 
24-hour-old bouillon cultures. These were allowed to stand 10 minutes, shaking 
at intervals; then beef agar plates were poured. The freshly transferred cultures 
were then frozen solid in a salt and ice mixture, kept frozen for 15 minutes 
and thawed in cool water. Plates were then again poured as before. From 
40 per cent to 60 per cent of the bacteria were killed by this treatment. 
Effect of sunlight. —Tests were made in Washington, D. C., in August. 
There were no clouds but the sky was not brilliantly clear. Plates poured from 
24-hour bouillon were exposed bottom side up on ice to the direct rays of the sun. 
One-half of each plate was protected from the sun by several folds of black paper. 
Exposures were made for 5, 10, 20, 30, 45, and 60 minutes. A colony count gave 
the following results: One-third were killed by a 5-minute exposure, one-half by 
10-minute, three-fourths by 20-minute and all by 45-minute and 60-minute ex¬ 
posures. 
Longevity. —The organism lives at room temperatures for six months in beef 
bouillon and in milk, or until the culture is actually almost completely evaporated. 
Group number. —The group number is 211.2322123 according to the descrip¬ 
tive chart of the Society of American Bacteriologists. 
