VACCINES EOGEE. 461 



For preventive inoculations the liquid (vaccinal lymph) collected 

 from the pustules of a child or from one of the Bovidse is used. The 

 animal vaccine is in general use to-day. Young calves are pre- 

 viously inoculated by numerous scarifications on the flanks, and 

 used for the culture of vaccine. It is to be hoped that the attempts 

 now being made will permit the cultivation of vaccinal virus in 

 artificial media so that the passage through animals will not be 

 necessary. 



According to their etymology the words " vaccine " and " vaccina- 

 tion" ought to apply only to the diseases of the cow and to its 

 inoculation. But, diverted from their original meaning, they desig- 

 nate to-day a whole series of viruses used for prophylactic purposes. 

 Thus, for instance, the terms anthrax vaccine and antianthrax vacci- 

 nations are used. Anthrax vaccine is used only in veterinary medi- 

 cine, but its study is valuable because the method has been the start- 

 ing point of numerous discoveries. 



To Toussaint, professor at the veterinary school of Toulouse, 

 belongs the credit for having first tried antianthrax vaccination. He 

 subjected anthrax blood to a temperature of about 55° for 10 minutes, 

 thinking in this way to kill the bacilli contained in it. Several 

 animals died on being inoculated Avith the blood thus prepared, but 

 those which survived became refractory. Toussaint believed that he 

 was vaccinating with the soluble products deposited in the blood 

 by the anthrax bacilli. As a matter of fact he was using weakened 

 microbes. This was shown by Pasteur, who in submitting anthrax 

 cultures to the action of heat, succeeded in producing vaccines which 

 could be accurately graduated. 



The most important of the Pasteur vaccinations consists in culti- 

 vating the anthrax bacilli at 42°. The microbe develops but does 

 not give off spores, and its virulence diminishes more and more. 

 If, after a certain length of time at 42°, the microbe is placed in a 

 new medium and raised to a eugenesic temperature of 37° or 38°, 

 it develops, gives off spores, but maintains the degree of weakness 

 which it had previously reached. There are two Pasteur vaccines — 

 one called the first vaccine, comes from a bacillus which is kept at 

 42° for from 15 to 20 daj^s; it is so weakened that it no longer has 

 the power to kill animals except those new born. The second vaccine, 

 which has remained for from 10 to 12 days at 42°, can still kill the 

 adults. 



In practice these two viruses, weakened but living, are inoculated 

 successively, and in this way sheep and cattle are rendered immune 

 with no attendant risk. The economic importance of this method 

 is readily seen, and man, who contracts anthrax only by contact 

 with animals, is indirectly protected. 



