BACILLUS ANTHRACI8. 503 



source from which to obtain non-spore-bearing anthrax 

 bacilli), prepare a hanging-drop preparation ; also a 

 cover-slip preparation in the usual way and stain it 

 with a strong gentian-violet solution; and another 

 cover-slip preparation which is to be drawn through 

 a flame twelve to fifteen times, stained with aniline 

 gentian-violet, washed in iodine solution and then 

 in water. Examine these microscopically. Do they 

 all present the same appearance? To what are the 

 differences due? 



Do the anthrax threads, as seen in a fresh, growing, 

 hanging drop, present the same morphological appear- 

 ance as when dried and stained upon a cover-slip? 

 How do they differ? 



Liquefy a tube of agar-agar, and when it is at the 

 temperatiire of 40° to 43° C. add a very minute quan- 

 tity of an anthrax culture which is far advanced in the 

 spore-stage. Mix it thoroughly with the liquid agar- 

 agar and from this prepare several hanging drops under 

 strict antiseptic precautions, using the fluid agar-agar 

 for the drops instead of bouillon or salt-solution. Select 

 from among these preparations that one in which the 

 smallest number of spores are present. Under the 

 microscope observe the development of a spore into a 

 mature cell. Describe carefully the developmental 

 stages. 



Prepare a 1 :1000 solution of carbolic acid in bouil- 

 lon. Inoculate this with virulent anthrax spores. If 

 no development occurs after two or three days at the 

 temperature of the thermostat, prepare a solution of 

 1 : 1200, and continue until the point is reached at 



