ANTHRAX. 



341 



FIG. 38. 



The bacterium in question, B. anthracis, is a typical rod- 

 shaped bacillus (Fig. 38), of moderate size (i /JL by 3-6 /V). It 

 is a rod with square ends and it multiplies by repeated divi- 

 sion, the elements remaining attached to form long chains. 

 Sometimes these long threads show no signs of the divisions 

 and, in certain media, they form marvelously twisted and con- 

 torted masses. It is motionless and multiplies with wonderful 

 rapidity. When in an active growing condition it is readily 

 killed by ordinary disinfecting agents, and by a moderate 

 heat, a temperature of about 160 F., easily destroying the 

 rods. But this bacillus produces spores which are very re- 

 sistant. The spores develop in the threads if there is an 

 abundance of oxygen. They are of good size (Fig. 38) and 

 may be most readily distin- 

 guished in anthrax cultures 

 as clear, glistening bodies. 

 It is their resistance to or- 

 dinary destructive agents 

 that makes anthrax so per- 

 sistent, and this high resis- 

 tance must be borne in 

 mind when the attempt is 

 made to disinfect a stable 



which has been occupied by an animal with this disease. 

 These spores will resist the action of 5-per-cent. carbolic 

 acid solution for half an hour, or a i-per-cent. solution 

 of corrosive sublimate for about the same length of time. 

 Few other living bodies can resist such treatment. The spores 

 will also resist high heat. When dry they can stand a tem- 

 perature of about 280 F. for two or three hours. When im- 

 mersed in liquid they are much more easily killed, since the 

 temperature of boiling, if maintained for a few minutes, is com- 

 monly sufficient to destroy them. While there are some bac- 

 terial spores which are more resistant than this, these anthrax 



B. anthrac2s,\.\\e cause of splenic fever. 



