EXPERIMENTS. 239 



tion, 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 this spore into a 

 mature cell. Describe carefully the steps. 



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 admits 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 

 tube into a second of the carbolic acid tubes ; when this 

 has developed, then from this into a third, etc. After 



