290 CLINICAL BACTERIOLOGY. 



On agar-agar a dense, creamy, coherent deposit forms ; and 

 upon potatoes a dry, whitish-gray layer. Blood- serum is lique- 

 fied. Milk is coagulated and pep to ni zed. 



Sporulation. If anthrax-cultures are exposed to tempera- 

 tures above 18 C. (64.4 F.), the bacilli soon exhibit spore- 

 formation. Slight development of spores takes place, besides, 

 down to the temperature-minimum. The anthrax-spore in- 

 variably lies exactly in the middle of the mother-cell, being 

 much shorter, but as wide, and possessing an oval shape. 

 After a time the germinating bacillus disintegrates, and the 

 spore is set free. If the spore is introduced into a sterile 

 hanging drop of bouillon, gelatin, or agar, its germination can 

 be accurately followed under the microscope (possibly with the 

 employment of a warm stage). The spore first loses its glis- 

 tening appearance, and increases in volume. Its membrane 

 then ruptures at one extremity and permits the escape of the 

 newly formed bacillus. The young bacillus enlarges in the 

 direction of the long axis of the spore, and soon throws off the 

 still adherent spore-membrane. Spore-formation takes place 

 only in the presence of free oxygen thus never in the'animal 

 body and never in the uninjured cadaver. 



The higher the temperature the more rapidly do the spores de- 

 velop at 37 C. (98.6 F.), as early as twenty hours; at 21 

 C. (69.8 F.), not before seventy-two hours; while above 42 

 C. (107. 6 F.) the anthrax-bacilli do not generate spores at 

 all. It is possible artificially to deprive the anthrax-bacilli of 

 their capability of generating spores. For this purpose it is 

 only necessary to add certain antiseptic substances to the nutri- 

 ent medium (Chamberland and Roux) : for instance, carbolic 

 acid in the proportion of from i : 600 to i : 1000, potassium 

 bichromate in the proportion of i : 2000. The bacilli culti- 

 vated upon such nutrient media remain sporeless permanently in 

 all subsequent generations, and in this way special asporogenous 

 anthrax-bacilli are developed. 



Resistance of Anthrax-bacilli and of Anthrax-spores. 



Anthrax-spores, like all other spores, are exceedingly re- 

 sistant structures ; while the fully developed bacilli suc- 

 cumb after exposure for a quarter of an hour to tempera- 

 tures in the neighborhood of 60 C. (140 F.), the spores 

 die in compressed steam at a temperature of 107 C. (224.6 

 F.) only after the lapse of five minutes ; and in live steam 

 at a temperature of 100 C. (212 F.) only after from twelve 

 to fifteen minutes. Five per cent, carbolic acid destroys the 

 mature forms of anthrax -bacilli in ten seconds, but the 

 spores not before from thirty-seven to forty days. In 



