33^ PATHOGENIC BACTERIA. 



increase in length a trifle, then to undergo a rupture at 

 one end, from which the new bacillus projects. The 

 spores of anthrax (Fig. no), being large and easily ob- 



r , 



FIG. no. Bacillus anthracis, stained to show the spores; x 1000 (Frankel 



and Pfeiffer). 



tainable, are excellent subjects for the study of sporula- 

 tion, for the action of germicides and antiseptics, and for 

 demonstration by stains. When dried upon threads of 

 silk they will retain their vitality for several years, and 

 are highly resistant to heat and disinfectants. 



Spores of anthrax are killed by five minutes' exposure 

 to a temperature of 100 C., and are killed in five minutes 

 in a 5 per cent, solution of carbolic acid, or, at least, are 

 deprived of their vegetative property in relation to cul- 

 ture-media. It is said by some that spores subjected to 

 5 per cent, carbolic acid can germinate when introduced 

 into susceptible animals. Spores are also killed by 

 simple wetting with i : 100,000 bichlorid-of-mercury so- 

 lution. 



The bacilli are not motile and are not provided with 

 flagella. They stain well with ordinary solutions of the 

 anilin dyes, and can be beautifully demonstrated in the 

 tissues by Gram's method and by Weigert's fibrin method. 



