Journal of Agricultural Research 
Vol. XXI, No. 3 
150 
Litmus milk. —Litmus milk blues rapidly and uniformly from the 
top downward, beginning on the second day. There is no coagulation, 
but a gradual uniform clearing. Reduction begins promptly, the color 
passing from blue to pale purplish gray (Ridgway, 1 Pl. LI 11 ), drab gray 
(Ridgway, PL XLVI), light drab (Ridgway, Pl. XLVI), and tawny 
olive (Ridgway, PL XXIX). Later the blue color returns. 
Methylene blue milk. —Milk to which methylene blue was added 
to make it robin’s egg blue shows reduction in color on the second day. 
In 1 o days reduction is complete. 
Cohn’s solution. —Usually no clouding occurs in Cohn’s solution. 
Occasionally very weak clouding takes place and a faint rim is formed. 
After six weeks in such cultures the fluid is clear with 3 to 6 mm. width 
of white precipitate which breaks up on shaking. 
Uschinsky’s solution. —In Uschinsky’s solution clouding is heavy 
with a viscid pellicle falling like that in beef broth, and a heavy viscid 
precipitate. 
Fermentation tubes. —In fermentation tubes containing 1 per cent 
peptone plus 1 per cent saccharose, dextrose, lactose, maltose, glycerin, 
or mannit there is good clouding in the open end, but none in the closed 
end, and no gas. All give a slightly alkaline reaction to neutral litmus 
paper at the end of two weeks. 
Litmus sugar agar. —Litmus agar containing 1 per cent peptone 
water plus 1 per cent saccharose, dextrose, lactose, maltose, galactose, 
or glycerin is not reddened. Moderately good growth occurs on all. 
Blood serum. —Growth on blood serum is moderate, with no liquefac¬ 
tion and no discoloration of the medium. 
Congo red agar. —On congo red agar little or no growth occurs, but 
in a few cases it was sufficient to show that the red color is taken up 
by the organism. 
Optimum reaction for growth in bouillon. —The organism grows 
best in +10 to +15 peptone-beef bouillon. It grows fairly well 
in +20 to +25 but not at all in +30. Growth is good in neutral 
bouillon and in —5 to —10, is weak in —15, very weak in -20, and 
no growth occurs in — 25. 
Toleration of acids. —Neutral peptone-beef bouillon was used, to 
which was added 0.1 per cent, 0.2 per cent, and 0.3 per cent of malic, 
tartaric, and citric acid, respectively. These titrated as follows: 
I o.i per cent +18 
.2 per cent +32 
.3 per cent +47 
{ 0.1 per cent +23 
.2 per cent +37 
.3 per cent +53 
! o. 1 per cent +24 
.2 per cent +40 
.3 per cent +53 
The organism grew readily in 0.1 per cent of all three acids, best in 
the malic, and weakest in the citric. No growth took place in 0.2 per 
cent or in 0.3 per cent of any of them. Other tests were made with 
1 Ridgway, Robert, color standards and color nomenclature. 43 P-» 53 pl* (col.). Wash¬ 
ington, D. C. 1912. 
