450 BACTERIOLOGY. 



to 38° C, but can also be brought to development at 

 from 16° to 18° C. Under 14° C. no growth is seen. 

 Spore-formation appears much sooner at the higher than 

 at the lower temperatures. When its spores are dried 

 upon bits of thread in the desiccator 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 the power of reproducing the disease for a long 

 time. The spores are tolerably resistant to the influence 

 of heat : when subjected to a temperature of 80° C. for 

 one hour their virulence is not affected, but an expo- 

 sure to 100° C for five minutes completely 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 

 tim«; 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. 

 The bacillus containing a spore has usually a clubbed 

 or spindle shape. 



It stains readily with the ordinary aniline dyes. It 

 is decolorized by Gram's method. Its spores may be 



