474 
Journal of Agricultural Research 
Vol. V, No. ii 
Hydrogen sulphid. —Strips of filter paper soaked in strong lead-acetate solution 
and dried were suspended over cultures in peptone-beef bouillon, milk, steamed 
potato, carrot, and turnip. No browning of the paper occurred within six weeks. 
Methylene blue IN milk. —Methylene blue is rapidly reduced. Cultures were 
made in milk containing 4 per cent of a 1 per cent solution of methylene blue. Bleach¬ 
ing begins on the second day and is complete or nearly so in six days, except for a 
pale-blue surface layer 2 to 4 mm. deep and a deep-blue rim and pellicle. This 
pellicle, when examined under the microscope, is seen to be composed of masses of 
bacteria that have taken up the stain. When shaken repeatedly, these bleached 
cultures regain their blue color. 1 
Blood serum. —Stroke cultures on Loeffier's blood serum give a moderate, white, 
shining filiform growth 3 mm. wide. There is no liquefaction even after eight weeks 
and no color change in the substratum. 
Aerobism. —The organism appears to be strictly aerobic. It does not grow in the 
closed end of fermentation tubes with any carbon food tested. In agar stab cultures 
no growth occurs in the lower end of the stab. Cultures were also made by shaking 
an inoculated tube of melted agar, but no growth occurred more than 3 mm. below 
the surface. Stabs were made in agar, then 10 c. c. of melted agar poured on top. 
No growth occurred in the stab or at the junction point, but there was good growth 
on the exposed surface of the added agar. 
Litmus agar with sugars. —On litmus-lactose-agar stroke cultures there is 
moderate growth and no color change. 
Stroke cultures on litmus-maltose agar give heavy growth, but do not alter the color. 
On litmus-saccharose agar growth is heavy and the medium reddens, beginning at 
the thin upper end. The reddening begins on the second or third day and is complete 
on the fifteenth day. 
Following the chart of the Society of American Bacteriologists, the 
group number is 211.23221*23. 
EFFECT OF COPPER SULPHATE ON THE ORGANISM 
Bouillon cultures 24 hours old were exposed to the action of chemically 
pure copper sulphate in the following manner. A dilution of copper 
sulphate (1 to 1,000) was made in a large Jena flask and allowed to stand 
overnight. After shaking thoroughly, further dilution was made again 
(in liter quantities) to 1 to 100,000 and 1 to 500,000. After these had 
been well shaken and had stood for an hour 10 c. c. of each were put 
into sterile test tubes and a loop of a well-clouded suspension from a 
24-hour-old agar culture was added. Plates were poured after 5, 10, 20, 
and 30 minutes from each tube, using carefully measured loops. Checks 
were made by pouring plates with the same measured loops from a 
similar dilution in sterile water. 
The plates were incubated at room temperature (27 0 to 30° C.). A 
colony count was made on the second day. Exposure to the 1 to 500,000 
dilution gave no observed reduction of colonies, but the 1 to 100,000 
destroyed nine-tenths of the organisms. The experiment was repeated 
with a strength of 1 to 50,000 of copper sulphate. All were killed at this 
exposure, while the check gave numerous colonies. 
1 The blue pigment is also absorbed by the bacteria from peptone water containing methylene blue. 
♦Nonchromogenic on most media, but green fluorescent in Usehinsky’s solution, Fermi’s solution, and 
old peptone-beef bouillon. 
