472 
Journal of Agricultural Research 
Vol. V, No. ii 
Gelatin stabs. —At 15 0 to 18 0 C. in +10 peptone gelatin the surface growth 
after seven days is about 6 mm. in diameter, with a pit of liquefaction 2 mm. wide and 
2 mm. deep. Stab growth is granular, not villous, fading out downward. As lique¬ 
faction progresses the upper part becomes stratiform, the lower part bluntly funnel- 
form (PI. XLIX, fig. 3). Liquefaction progresses rather slowly but is complete within 
three to four weeks at the specified temperatures. 
BEER bouillon. —In +15 peptone-beef bouillon uniform clouding occurs within 24 
hours. This clouding is weak to moderate, never strong. On the second day a mem¬ 
branous pellicle is formed, which fragments and falls readily on shaking. It is made 
up of a homogeneous mass of bacteria—i. e., free from pseudozoogloeae but containing 
a few short chains (10 or 12 individuals). Old cultures (4 to 6 weeks old) are often 
decidedly green fluorescent. The white precipitate breaks up readily on shaking 
and contains many small crystals. 
Potato cylinders. —When inoculated from agar cultures growth on steamed 
potato cylinders in two days is moderate, spreading, creamy white, shining, and 
slimy. The part of the potato out of the water becomes slightly browned. Growth 
on potato soon ceases. After 10 days the color of the potato is completely changed, 
becoming a pale brownish hue, and the growth takes on a similar color (very pale 
brownish). Tested with alcohol iodin for starch, such cultures give a heavy dark- 
purple reaction, showing that there has been only a partial digestion of the starch 
(formation of amylodextrin). The cylinders are not softened. 
Milk. —Inoculated milk clears slowly and without coagulation. Clearing begins 
within a week, and after two weeks tubes of it are translucent so that the outlines 
of a pencil back of the milk may be seen through it clearly. Cultures 1 month old 
are still clear but are then tawny olive, 1 with a darker rim where the milk has dried 
down. 
Litmus milk. —Lavender-colored litmus milk begins to blue from the top down¬ 
ward on the second day and is completely blued by the third day, without a sign 
of coagulation or clearing. A decided creamy-white pellicle is formed. 
After 10 days clearing begins and is complete in 20 days. Later the blue color 
bleaches out (reduction phenomena), beginning at the bottom, leaving the whole 
fluid a clear (translucent) brown. At no time is there any reddening of the litmus 
or any coagulation of the milk; nor are any crystals formed in it. 
Fermentation tubes. —The tests in fermentation tubes were made in water 
containing 2 per cent of Witte’s peptone, to which was added 2 per cent of the carbon 
compound to be tested—namely, saccharose, dextrose, lactose, maltose, glycerin, 
and mannit. Clouding occurred in the open end of each on the second day, heaviest 
in the tubes containing saccharose and dextrose, but the closed end in every case 
remained clear, with a distinct line across the inner part of the U. When 5 days 
old they were tested with neutral litmus paper. Saccharose and dextrose gave a 
decidedly acid reaction, while all the others were neutral. When 20 days old the 
saccharose and dextrose were still acid and the others weakly alkaline. No gas was 
formed and no growth occurred in the closed end of any. 
No gas was formed in fermentation tubes containing sterile milk; nor was there 
any separation of the curd. The milk in the open end cleared gradually, while 
that in the closed end remained unchanged. The litmus reaction was alkaline in the * 
open end. 
Nitrate bouillon in fermentation tubes gave a good clouding in the open end, none 
in the closed end, no gas, and no nitrate reduction. A decided alkaline reaction was 
obtained with neutral litmus paper. 
Toleration or sodium chlorid. —Neutral peptone-beef bouillons containing 2, 5, 
6, and 7 per cent of chemically pure sodium chlorid, respectively, were inoculated 
from young bouillon cultures. Growth was retarded by 2 per cent of sodium chlorid 
1 Ridgway, Robert. A nomenclature of colors ... 129 p., 17 pi. (partly col.). Boston, 1886. 
