302 ANTHRAX; AND HYDROPHOBIA. 



A stab culture in gelatin develops quite rapidly and luxuri- 

 antly on the surface and along the track of the needle. From 

 this whitish linear growth numerous fine, hair like projections 

 extend out into the medium. Liquefaction begins at the sur- 

 face, and is complete within a few weeks, when the growth is 

 precipitated. 



The growth on agar-agar plates is the same as that on 

 gelatin plates, but more distinct. The medium is not lique- 

 fied. Agar stroke cultures are not at all characteristic. A 

 thin wrinkled layer, with irregular edges, forms along the 

 line of inoculation, and a few fine threads project from the 

 central growth. Sporulation occurs most rapidly on agar- 

 agar. In old cultures the medium is turned a deep brown. 



In bouillon development is quite rapid, the growth forming 

 in small flaky masses which rapidly settle to the bottom of 

 the tube, leaving the supernatant fluid perfectly clear. 

 Growth on blood-serum is very sparse ; the medium is slightly 

 liquefied. On potato a thick dry white membrane is formed. 

 All the culture-media should be slightly alkaline, as the 

 anthrax bacillus will not grow in the presence of even a very 

 small quantity of free acid. 



Vitality : One of the characteristics of the anthrax bacil- 

 lus, and especially its spores, is the resistance to heat and 

 chemicals. The mature bacilli can withstand a temperature 

 of 60 C. for fifteen minutes. The spores survive live steam 

 at a temperature of 100 C. for from ten to fifteen minutes ; 

 compressed steam, for five minutes. A 5 per cent, solution 

 of carbolic acid kills the bacillus in ten seconds, and the 

 spore in from thirty-five to forty days. A 1 : 1000 solution 

 of bichloride destroys the spores in about twenty hours. 

 When kept in sterilized water the spores live for many 

 months, but the bacillus dies in about three days. The bacil- 

 lus is not able to resist putrefaction, but the spores retain 

 their vitality. 



Pathogenesis : Anthrax is a disease of animals, but is met 

 with in man when the individual comes in contact with 

 anthrax infected animals. Shepherds, tanners, and butchers 

 are especially predisposed to the infection because of their 

 occupation, which necessitates handling of the carcass, and 



