ANTHRAX 159 



growth takes place along the needle track, fine branching 

 filaments often growing out into the gelatine. Liquefaction 

 commences at the top of the stab, proceeding downwards in 

 a horizontal plane, upon which a mass of bacilli rest, leaving 

 the gelatine above clear and liquid. No pellicle is formed 

 on broth cultures. On agar-agar a thin, gray- white growth 

 takes place, and on potato a considerable white growth, both 

 usually containing a large number of spores. Blood serum 

 is slowly liquefied. An alkaline reaction is generally favour- 

 able to the growth of this organism, but it will be noted 

 above that it grows well on potatoes, which are normally 

 acid. The bacilli stain well and easily with aniline dyes, 

 and are not decolourised by Gram's staining method. The 

 spores have great resisting powers to all reagents, and can 

 only be stained by heating for twenty minutes or more on 

 warm carbol-fuchsine, or by first ' flaming ' nine to a dozen 

 times. 



The spores will retain their vitality unimpaired for years 

 if kept dry and not much exposed to the light. 



Direct sunlight has an inhibitory and injurious effect on 

 both bacilli and spores. It is stated by Schild that the 

 spores are destroyed in one hour by a O'l per cent, solution 

 of formalia Boiling kills the bacilli in a few seconds, while 

 the spores may be able to resist this treatment for ten minutes 

 or more. The spores will live in a 1 per cent, solution of 

 phenol for a week, whereas the bacilli may die in two 

 minutes, and a 5 per cent, solution will only kill the spores 

 in about twenty-four hours. In the interior of a body 

 dead of anthrax, the specific bacilli are killed off by a putre- 

 factive organism in about a week. The spores of anthrax, 

 being among the most hardy of the common bacteria, are 

 often used in the testing of disinfectants, but it must here 

 be remembered that the spores from various sources are not 

 uniform in their powers of resistance. 



