BACILLUS ANTHRAC1S. 385 



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 differ- 

 ences 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. 



Prepare a 1 : 1000 solution of carbolic acid in bouillon. 

 Inoculate this with virulent anthrax spores. If no de- 

 velopment occurs after two or three days at the tempera- 

 ture of the thermostat, prepare a solution of 1 : 1200, 

 and continue until the point is reached at which the 

 amount of carbolic acid present just permits of the de- 

 velopment of the spores. When the proper dilution is 

 reached prepare a dozen of such tubes and inoculate one 

 of them with virulent anthrax spores. As soon as de- 

 velopment is well advanced, transfer a loopful from this 



