PATHOGENIC BACTERIA. 275 



some danger to the inoculated animals attending the use of 

 anthrax vaccines. 



In order to obtain material free from spores the blood of 

 an animal which has recently died of anthrax is taken, because 

 anthrax spores do not form in the Uving body. Cultures made 

 in bouillon are kept at a temperature of from 42° to 43° C. 

 At this temperature spores do not form, while the virulence of 

 the anthrax bacillus becomes gradually diminished. In time 

 the virulence is so far diminished that rabbits will survive 



\ 



V 



■v 





y 



\ 



V 



\. 



Fig. 79. — Anthrax Bacilli with Square or Slightly Concave Ends 

 Sometimes Seen; Fuchsin Stain. (X 1000.) 



inoculation, and eventually also mice and guinea-pigs, which 

 are extremely susceptible to anthrax. Small doses of a culture 

 of extremely weak virulence are given to the animals which it 

 is desired to protect, Hke cattle and sheep, and subsequently a 

 somewhat more virulent culture is employed.* The method is 

 never used in human beings. 



Bacillus influenzae. — ^A small bacillus, 0.2 to 0.3 n by 0.5 ji, 

 with rounded ends. It does not form spores, is not motile 



* For details as to the results of this method see V. A. Moore. Infectious 

 Diseases of Animals. 1902. For other and unique researches on immunity 

 for anthrax see Emmerich. Centralblatt fur Bakteriologie. Original. Bd. 

 XXXII. P. 821. 



