BA CILL US ANTHBA CIS. 423 



temperature of from 18° to 20° C. Examine them 

 each day. Do they develop in the same way ? 



From a fresh culture of anthrax bacilli, in which 

 spore-formation is not yet begun (which is the surest 

 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 

 the flame twelve to fifteen times, stained with aniline 

 gentian-violet, washed off 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 

 temperature 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. 



