B. ANTHRACIS: EXPERIMENTS. 365 



The amphibia, dogs, and the majority of birds are 

 not susceptible to this disease. Rats are difficult to infect. 

 Rabbits, guinea-pigs, white mice, gray house-mice, sheep, 

 and cattle are susceptible. Infection may occur either 

 through the circulation, through the air-passages, through 

 the alimentary tract, or, as we have just seen, through 

 the subcutaneous tissues. 



Experiments. 



Prepare three cultures of anthrax bacilli — one upon 

 gelatin, one upon agar-agar, and one upon potato. Allow 

 the gelatin culture to remain at the ordinary temperature 

 of the room, place the agar culture in the incubator, and 

 the potato culture at a temperature not above 18° to 

 20° C. Prepare cover-slips from each from day to day. 

 What differences are observed ? 



Prej^are two potato cultures of the anthrax bacillus. 

 Place one in the incubator and retain the other at a tem- 

 perature 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, prepare a hanging- 

 drop preparation ; also a cover-slip preparation in the 

 usual way and stain it with a strong gentian- violet solu- 

 tion, and another cover-slip preparation which is to be 

 drawn through the flame twelve to fifteeen times, stained 

 with aniline gentian-violet, washed off in iodine solu- 

 tion and then in water. Examine these microscopically. 

 Do they all present the same appearance ? To what are 

 the differences due? 



