RESISTANCE OF THE ANTHRAX BACILLUS AND ITS SPORES 247 



the peptonizing ferment of bacteria digests and fluidifies gelatin, 

 blood serum, egg-albumen, etc., but not agar. Agar stick cultures 

 also resemble gelatin stick cultures, except for the absence of lique- 

 faction, and the inverted pine-tree effect is often well produced. On 

 agar slants gray, granular, shiny growths develop, which later become 

 uneven and folded and cannot be very easily removed from the surface 

 for microscopic examination without the use of some force with the 

 platinum loop. On potatoes the anthrax bacillus grows very luxuri- 

 antly, forming a whitish, dull, shining mass, and the spore formation 

 is generally very abundant and seen early. The growth on blood 

 serum, as on gelatin, leads to liquefaction. Sterile milk is first coagu- 

 lated by the anthrax bacillus, later the precipitated casein is liquefied. 

 Fresh unpasteurized or unsterilized milk is not a favorable culture 

 soil, because the developing lactic acid bacteria prevent the growth 

 of anthrax bacilli causing them very soon to die out completely, 

 unless spores have previously been formed. In bouillon the growth 

 of the heavy non-motile bacilli leads to the formation of slimy flocculi 

 which sink to the bottom. From this sediment filamentous masses 

 arise, but the 'upper layers of the fluid generally remain clear. 



Resistance of the Anthrax Bacillus and its Spores. The vegetative 

 form of the anthrax bacillus is not very resistant to inimical germi- 

 cidal and physical influences, but the spores are much more resistant 

 than those of most other pathogenic bacteria; tetanus spores, 

 however, withstand moist heat better than anthrax spores. Anthrax 

 bacilli are killed when heated to 55 C. for forty minutes if contained 

 in fresh blood, and in one hour if heated to 50 C. A spore-free 

 bouillon culture is killed if exposed for five and one-half minutes to 

 65 C., and in three minutes if heated to 75 C. Dry air of 140 C. 

 kills anthrax spores only after three hours' exposure; steam of 95 C. 

 after ten minutes; steam of 100 C. after five minutes. Low tempera- 

 tures as they ordinarily occur in nature in countries of medium 

 latitude have no appreciable effect upon either bacilli or spores. 

 Direct sunlight kills bacilli and spores in a comparatively short time, 

 particularly when the air has free access while the rays are acting 

 upon the organism. Bacilli are easily killed by a 1 to 1000 solution of 

 corrosive sublimate, and even spores are killed after a few hours, 

 but this powerful action is only obtained when the solutions act upon 

 dry bacilli or spores or when the latter are suspended in a watery 

 solution. In the presence of albumin, as in blood, the action of mer- 

 cury bichlorid is untrustworthy. Carbolic acid in watery solutions 

 acts weakly toward spores. Salting and curing of meat kill anthrax 

 bacilli in from two to four weeks, but has no effect upon the spores. 

 The most markedly antagonistic bacterium to the anthrax bacillus 

 is the Bacillus pyocyaneus. If a mixed culture of anthrax and 

 pyocyaneus is made the latter will develop and the former will die 

 out. This effect is probably due to a ferment secreted by the 

 Bacillus pyocyaneus, and known as pyocyanase. The streptococcus 



