370 



SCIENCE 



[N. S. Vol. XXXVIII. No. 976 



two latter media being used as controls. The 

 media were freshly made as needed. A number of 

 potatoes were cut into cylinders, washed in run- 

 ning water for about an hour and then allowed to 

 remain in a basin of water over night. One third 

 of the lot was placed into 6 per cent, glycerine 

 broth, and one third into plain broth for about 

 two hours, and the remainder was left in the 

 water. The three batches of potatoes were then 

 tubed and glycerine broth and plain broth were 

 poured into the tubes up to the level of the gly- 

 eerinated and broth potato, respectively. The 

 plain potato had no fluid added to it. The media 

 were then sterilized in the autoclave at 18 lbs. 

 pressure for 15 minutes, and then stored until 

 used in cold place to prevent drying. The plants 

 were all made of the same stock cultures, at the 

 same time incubated both at 22° and 37.5° C. 

 Each test was carried out a number of times, to 

 assure constant resiilts. The results obtained will 

 for convenience be divided into three groups. The 

 first comprising bacteria that show a striking con- 

 trast in their cultures on the different potato 

 media; the second showing a slight difference, 

 and the third those showing no difference. The 

 first group includes the following microorganisms: 



Two different strains of B. maUei of himian 

 source. 



One strain of B. mallei received from New York. 



Two strains of Actinomyces received from "Wash- 

 ington. 



B. pyocyaneus, old stock culture. 



B. siibtilis, old stock culture. 



An unidentified spore-forming bacillus, isolated 

 from the intestinal tract of a rabbit and 

 designated as "B. rabbit spore." 



To sum up this group: The three strains of the 

 glanders bacillus give lighter colored, moister and 

 more typical honey-like growths on glycerine po- 

 tato. Their growth on plain potato is more 

 brownish yellow in color and the potato is usually 

 discolored. A metallic luster was noted on broth 

 potato on several occasions with each strain. The 

 Actinomycetes give a dry culture made up of iso- 

 lated colonies, raised and of decided brown color 

 on plairi potato, whereas on glycerinated potato 

 they give rise to a luxuriant growth of more con- 

 glomerated colonies of a honeycomb-like arrange- 

 ment and of a light-yellow color. The B. pyocy- 

 aneus gives a brighter and deeper green pigment 

 on the glycerine medium and a brown or green- 

 brown slimy growth on ordinary potato. The B. 

 prodigiosus gives a bright cherry-colored growth 

 on glycerine potato and agar, at 22° C, a slight 

 red or orange on broth potato and a faint pink 



on ordinary potato. It gives hardly any color at 

 37.5° C, on any of the media. The B. subtilis 

 apparently grows better on ordinary potato, pro- 

 ducing a heavy furred culture of brown color. 

 On the glycerine potato it gives a rather delicate 

 lightly furred growth of a light-yellow color. In 

 the second group are included: 



B. eoli, stock culture. 



B. mucosus, stock culture. 



Sp. clwlera, stock culture. 



An unidentified organism isolated from rabbit 



feces, here designated as " B. rabbit feces. ' ' 

 An unidentified pleomorphic bacillus isolated 



from a contaminated plate. 

 A mould. 



In general it may be stated that these organisms 

 do not show striking differences in their growths 

 upon the three varieties of potato. Glycerinated 

 potato permits as a rule a much lighter colored 

 growth, less raised, and often more homogeneous 

 in character. In the third group are included the 

 diphtheria, typhoid, dysentery and grass bacillus, 

 the Streptococcus pyogenes, Staphylococcus aureus 

 (two strains), Sarcina aurantia and a yeast. 

 There are no visible differences in the cultural 

 characters of each of these organisms on the 

 potato media under consideration. The chromo- 

 genie organisms (Sarcina aureus, yeast) seemed 

 to give brighter and more intense pigment produc- 

 tion and at times somewhat more luxuriant 

 growths on the glycerinated potato. In conclusion 

 the writer desires to bring to your attention that 

 with the particular strains used glycerinated po- 

 tato affords a more favorable medium for most of 

 the twenty-five microorganisms tested. It allows 

 more moist, more homogeneous, less raised growth 

 characteristics, of lighter or brighter color. With 

 the B. prodigiosus the color was greatly intensi- 

 fied. Glycerine potato is seldom discolored, 

 whereas both broth and plain potato are frequently 

 discolored, particularly the latter. From the above 

 we may conclude that a more general use of gly- 

 cerinated potato suggests itself. 



The Preservation of StocTc Cultures: A. Pakker 



Kitchens, Glenolden, Pa. 



For the preparation of stock bacterial vaccines 

 it is necessary to have constantly on hand a large 

 number of cultures of the various pathogenic bac- 

 teria. For the preparation of vaccines for the 

 treatment of the various regional mixed infections, 

 it is deemed necessary to collect the various spe- 

 cies and types in each region. To keep fresh stock 

 of any culture frequent transplantation is neces- 

 sary. As the intervals between transplants vary 



