488 
Journal of Agricultural Research 
Vol. XXIII, No. 6 
Litmus milk. —The color becomes more intense on the second day, 
with the formation of a thin blue layer in the upper portion of the 
medium which disappears about the third day. After 4 days the casein 
is precipitated, and in 6 more days the clearing has proceeded two- 
thirds of the way down the tube. The liquid is dark green on top 
and shades down to a tan just above the casein. The medium on long 
standing finally becomes a deep blue-green. 
Cohn’s solution. —Marked clouding occurs in 2 days or less, fol¬ 
lowed in about 4 days by the appearance of a heavy white crystalline 
membrane on the surface and a faint greenish tinge below it. On long 
standing the medium becomes light yellow in color and contains a 
flocculent precipitate. 
Fermi’s solution. —Clouding becomes very marked after 2 days. 
After about 8 days the medium takes on a light greenish tinge, but this 
is not as marked as with Bacterium tabacum . After about 10 days or 
more a fairly heavy membrane is formed and the sediment increases. 
On longer standing the medium turns to an intense honey-yellow color. 
Beet agar stroke. —On beef agar slants growth is distinct in 24 
hours, grayish white in color, turning finally to a deeper yellow. Growth 
less profuse than on potato agar and no coloring of medium evident. 
LoefflEr’s blood serum. —Growth grayish yellow, spreading, re¬ 
sulting in gradual liquefaction of medium. 
^ Nitrate in nitrate broth. —There was no reduction of nitrates in 
nitrate peptone broth. 
Indol, ammonia, and hydrogen sulphid. —Negative tests for all by 
usual methods. 
Fermentation tests. —From a 2 per cent Difco peptone solution five 
different carbon media were made by adding 1 per cent of the following: 
Saccharose, dextrose, lactose, glycerine, and dextrin. In fermentation 
tubes no gas was formed with any of these compounds. Distinct cloud¬ 
ing appeared in the open arms in 48 hours. In the case of saccharose and 
dextrose slow clouding also appeared in the closed arms. No acid was 
produced in any of the tubes. 
Litmus sugar agars. —Tests with lactose, glycerine, saccharose, 
dextrose, dextrin, agars showed no formation of acid in any case. 
Toleration of acids and sodium chlorid. —No growth was obtained 
in tubes of neutral beef-peptone broth to which 0.3 per cent of malic, 
citric, or tartaric acid had been added (P H values 3.6 to 4.0). A concen¬ 
tration of 0.2 per cent of malic and tartaric limited growth but 0.2 citric 
did not. Two to 3 per cent sodium chlorid limited growth markedly 
and 4 per cent inhibited growth entirely. 
Optimum reaction and toleration limits. —The best growth in 
beef-peptone broth was secured at + 10 to + 15 Fuller’s scale. The 
maximum for growth lies apparently close to + 20, + 22 giving no 
growth. While good growth was secured in some instances as low as 
— 20 it is not believed that these results are significant, since the broth 
after adjustment and standing for some time usually rose to —4 or 
higher. 
Temperature relations. —The optimum for growth in culture lies 
close to 26° to 28° C. No growth was secured at 35 0 to 36° or below 
7° to 9 0 . The thermal death point found by subjecting freshly inoculated 
tubes of boullion to different temperatures for 10 minutes was found to 
be about 57 0 . 
