200 
Journal of Agricultural Research 
Vol. I, No. 3 
Gentian-Violet Agar. —Growth of the bacterium on gentian-violet 
agar was very slow, no growth being visible in 4 days and only a 
slight growth in 18 days. When examined four weeks after inocu¬ 
lation, however, a thin bluish growth was observed along the stroke and 
spreading from the base over the surface of the slant. The medium had 
paled, some of the violet color having been extracted by the bacterium 
in its growth. 
OTHER CULTURAL FEATURES OF THE ORGANISM 
Nitrates. —Nitrates are not reduced. Tests were made with nitrate 
bouillon cultures 5 and 10 days old in the following manner: 1 c. c. of a 
potato-starch solution was added to each culture, then 1 c. c. of a fresh 
potassium-iodid solution (11250), after which 5 drops of dilute sulphuric 
acid (2:1) were added. There was no change of color in any of the 5 
or 10 day old cultures. 
Indol* —No indol is present in cultures 1 to 10 days old. It is present, 
however, in cultures n to 25 days old. The tests were made as follows: 
Transfers were made from a 2-day-old bouillon culture to Uschinsky’s 
solution containing 2 per cent of peptone. These cultures grew at room 
temperature, 20° to 24 0 C., tests being made at the end of 1, 3, 5, 8, 10, 
11, 12, 13, 15, and 25 days. Ten drops of concentrated sulphuric acid 
were added to each culture to be tested and after standing for five min¬ 
utes, 1 c. c. of a 0.02 per cent solution of sodium nitrite was added. If 
no pink color was visible in the cultures five minutes after adding the 
nitrite, the tubes were heated to a temperature between 70° and 8o° C. 
The rose color which indicates the presence of indol was not present in 
any of the tests up to the tenth day. 1 Indol was present in some of the 
11-day cultures, but in the 15-day and 25-day cultures each one gave 
the definite rose-color reaction. 
TEST FOR HYDROGEN SULPHID 
No hydrogen sulphid is produced. Litmus-lactose agar slants were 
inoculated from a 2-day beef-agar culture. Small strips of filter paper 
previously moistened in a saturated solution of lead acetate were inserted 
in the tubes, being held in place by means of cotton plugs in such a man¬ 
ner as to prevent contact with the medium. In two days there was 
growth along the entire stroke, accompanied by a bluing of the agar, but 
without any discoloration of the filter paper. In six days the bacterial 
growth had become abundant, spreading at the base of the stroke and 
filling the condensation water. During a period of four weeks there was 
no evidence of hydrogen sulphid. The test was repeated with litmus- 
lactose agar, beef agar, and beef-bouillon cultures with the same result. 
1 In a few instances a faint pinkish color appeared on the tenth day in tests made with the nasturtium 
strain of the organism. 
