PATHOGENIC BACTERIA 



107 



Properties. Liquefies gelatin; immotile; the spores are very 

 resisting, living twenty years, and resist boiling for five minutes. 



Growth. Grows rapidly, between 12 C. and 45 C., and 

 requires plenty of oxygen, but may be classed as a facultative 

 anaerobe; grows well in all media. 



Plates of Gelatin. Colonies develop in two days; white shiny 

 spots, which appear under microscope as slightly yellowish 



-- ~~ --^Tv^ ,^ 



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Figs. 55, 56. Stab-cultures of anthrax in gelatin. 



granular twisted balls, like a ball of yarn; each separate string 

 or hair, if looked at under high power, being composed of bac- 

 teria in threads. 



Stab-cultures. A white growth with thorn-like processes 

 along the needle-track; later on, gelatin liquefied, and flaky 

 masses at the bottom. (See Figs. 55, 56.) 



Potato. A dry, creamy layer, and when placed in brood-oven, 

 rich in spores. 



