422 BACTERIOLOGY. 



are employed. These were designated by Pasteur as 

 " first 7 ' and " second 77 vaccines. The " first 77 is the 

 one that killed only the mice in the preliminary tests, 

 while the " second 77 is that which killed both mice and 

 guinea-pigs, but failed to kill the rabbit. When larger 

 animals, such as sheep or cattle, are to be protected by 

 vaccination with these vaccines, a subcutaneous inocu- 

 lation of about O.f3 c.c. of the first vaccine is usually 

 given. This should be practically without noticeable 

 effect, causing neither rise of body-temperature nor 

 other constitutional or local symptoms. After a period 

 of about two weeks the second vaccine is injected in 

 the same way; this may or may not cause disturbance. 

 In the event of its doing so the symptoms are rarely 

 alarming, and, if the vaccines have been properly pre- 

 pared and tested before use, they disappear within a 

 short time after the injection. 



In the large majority of cases sheep, bovines, horses, 

 and mules may be safely protected against anthrax by 

 the careful practice of this method. 



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 tempera- 

 ture of the room, place the agar-agar culture in the in- 

 cubator, 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 ? 



Prepare two potato cultures of the anthrax bacillus. 

 Place one in the incubator and maintain the other at a 



