42 MANUAL OF EQUINE MEDICINE. 



found enormous numbers of rods, 5 to 20 /v. long by about 

 1 /x broad, straight and motionless. 



In a suitable culture-material, with a good supply of 

 oxygen and a temperature between 15° and 42° C, the rods 

 develop into very long filaments. In these filaments, round, 

 highly refractile spores form at short and regular intervals. 

 The filaments then break up, and the spores escape and may 

 grow into bacilli. In living animals the rods multiply 

 solely by division, and long filaments and spores are never 

 found. 



The rods are found in enormous quantities, especially in 

 the spleen, lungs, liver, kidneys, mucous membrane of the 

 intestines, and in various other parts. 



Bacillus Anthracis is always present in splenic fever in 

 enormous numbers. The bacilli may be separated and 

 washed with distilled water, alcohol, ether, and dried ; yet 

 they still cause anthrax fever when inoculated into animals. 

 Pure cultivations through fifty generations may be made 

 with the same result. This germ always gives rise to anthrax 

 fever, and never to any other. Therefore, in conclusion, we 

 recognise in this germ the direct cause of this malady. 



Now, M. Pasteur asserts that he has succeeded in modify- 

 ing the micro-organism of anthrax by artificial cultivation, 

 and that by inoculating animals with the attenuated virus 

 he is able to cause a mild form of the disease, conferring a 

 certain immunity against future attacks. 



Pasteur's Method of Preparing Vaccine, or Attenuated 

 Virus of Anthrax. — A drop of blood, on a glass rod, is 

 taken from an animal in the last stage of anthrax. It is 

 now placed in a suitable clear pabulum, such as fowl broth, 

 previously rendered sterile by subjecting to a temperature 

 of 115° C. The vessel containing the fluid is kept in pure 

 air at a temperature of 42^ to 43° C. The fluid gradually 

 becomes cloudy, but no spores are developed. 



