474 Journal of Agricultural Research voi.v. no. u 



Hydrogen sulphid. — Strips of filter paper soaked in strong lead-acetate solution 

 and dried were suspended over culttu-es in peptone-beef bouillon, milk, steamed 

 potato, carrot, and turnip. No brow-ning of the paper occmred withio six weeks. 



Methylene blue in milk. — Methylene blue is rapidly reduced. Cultures were 

 made in milk containing 4 per cent of a i per cent solution of methylene blue. Bleach- 

 ing begins on the second day and is complete or nearl}^ 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. ^ 



Blood serum. — Stroke cultures on Loeffler'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 poiu-ed on top. 

 No gro-wth occurred in the stab or at the junction point, but there was good growth 

 on the exposed sixrface 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. 



Follovnng 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 (i 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 i to 100,000 and i 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° to 30° C). A 

 colony count was made on the second day. Exposure to the i to 500,000 

 dilution gave no observed reduction of colonies, but the i to 100,000 

 destroyed nine-tenths of the organisms. The experiment was repeated 

 with a strength of i 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 Uschinsky's solution, Fermi's solution, and 

 old peptone-beef bouillon. 



