THE BACILLUS OF SYMPTOMATW ANTHRAX. 531 



upon bits of thread in the dessiccator over sulphuric acid, 

 and then kept under ordinary conditions, they retain 

 their vitality and virulence for many months. Sim- 

 ilarly, bits of flesh from the affected areas of animals 

 dead of this disease, when completely dried, are seen to 

 retain for a long time the power of reproducing the 

 disease. The spores are tolerably resistant to the in- 

 fluence of heat : when subjected to a temperature of 

 80° C. for one hour their virulence is not affected, but 

 an exposure to 100° C. for five minutes destroys 

 them. They are also seen to be somewhat resistant to 

 the action of chemicals : when exposed to 5 per cent, 

 carbolic acid they retain their disease-producing prop- 

 erties for about ten hours, whereas the vegetative forms 

 are destroyed in from three to five minutes ; in corro- 

 sive sublimate solution of the strength of 1 : 1000 the 

 spores are killed in two hours. 



When gelatin cultures are examined microscopically 

 the organisms are usually seen as single rods with 

 rounded ends. When cultivated in agar-agar at a 

 higher temperature spores are formed after a short 

 time ; the spores are oval, slightly flattened on their 

 sides, thicker than the bacilli, and, as stated, frequently 

 occupy a position inclining to one of the poles of the 

 bacillus, though they are as often seen in the middle. 



Bacilli containing spores are usually clubbed or spin- 

 dle shape. 



This bacillus stains readily with the ordinary aniline 

 dyes. It is decolorized by Gram's method. Its spores 

 may be stained by the methods usually employed in 

 spore-staining. 



Pathogenesis. — When susceptible animals, especi- 

 ally guinea-pigs, are inoculated in the deeper subcutane- 



