A text-book of bacteriology / by George M. Sternberg.

  • Sternberg, George Miller, 1838-1915.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of bacteriology / by George M. Sternberg. Source: Wellcome Collection.

    373/748 (page 343)
    a small quantity of agar to a gelatin medium prevents liquefaction of the gelatin (Flugge). Upon blood serum a rather thick, white layer is formed and liquefaction slowly occurs. Upon potato the growth is abundant as a rather dry, grayish- white layer, of limited extent, having a somewhat rough surface and irregular margins. Spores are formed only in the free presence of oxygen, as in sur- face cultures upon potato or nutrient agar, or in shallow cultures in liquid media, and at a temperature of 20° to 35° C. They are not formed during the development of the bacilli in the bodies of living a Fig. 103.—Colonies of Bacillus anthracis upon gelatin plates : a, at end of twenty-four hours; b, at end of forty-eight hours, x 80. (Flugge.) animals, but after the death of the animal the bacillus continues to multiply for a time, and spores may be formed where the fluids containing it come in contact with the air—as, for example, in bloody discharges from the nostrils or from the bowels of the dead animal. Varieties incapable of spore production have been produced arti- ficially, by several bacteriologists, by cultivating the bacillus under unfavorable conditions. Roux was able to produce a sporeless va- riety by successive cultivation in media containing a small quantity of carbolic acid—1 :1,000. V arieties differing in their pathogenic power may also be pro- duced by cultivation under unfavorable conditions. Thus Pasteur