624 APPLICATION OF METHODS OF BACTERIOLOGY 



accompanied by the production of gas-bubbles. There is 

 produced at the same time a peculiar, penetrating odor 

 somewhat suggestive of that of rancid butter. Under these 

 conditions spores are formed after about thirty hours. 



It grows well in bouillon of very slightly acid reaction 

 under hydrogen, but does not retain its virulence for so 

 long a time as when cultivated upon solid media. In this 

 medium it develops in the form of white flocculi that sink 

 ultimately to the bottom of the glass and leave the super- 

 natant fluid quite clear. If the vessel be now gently shaken, 

 these delicate flakes are distributed homogeneously through 

 it. In bouillon cultures there is often seen a delicate ring 

 of gas-bubbles round the point of contact of the tube and 

 the surface of the bouillon. There is produced also a pecu- 

 liar, penetrating, sour or rancid odor. 



It grows best at the body-temperature i. e., from 37 to 

 38 C. but can also be brought to development at from 

 16 to 18 C. Below 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. Similarly, 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 resist- 

 ant to the influence of heat: when subjected to a tempera- 

 ture 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 exposeo! to 5 per cent, carbolic acid 

 they retain their disease-producing properties for about 



