8 DR. E. KLEIN. 



of attenuated virulences; everything is similar to what happens 

 In respect to the microbe of chicken cholera. Further, each of 

 these conditions of attenuated virulence may be reproduced by 

 culture. Lastly, since splenic fever does not recur (ne reci- 

 dive pas), each of our attenuated anthracoid microbes consti- 

 tutes for the superior microbe a vaccine, that is to say, a virus 

 capable of producing a milder disease. Here, then, we have a 

 method of preparing the vaccine of splenic fever." 



[These are stated as general propositions, and M. Pasteur 

 makes them without mention of any particular kind of animal. 

 He cultivates the anthrax bacillus at 42 C°. in fowl-broth, 

 and treats as indifferent the class of animal into which he 

 inoculates the cultivation.] 



" I was asked to give a public demonstration at Pouilly-le- 

 Fort, near Melun, of the results already mentioned. This 

 experiment I may relate in a few words. Fifty sheep were 

 placed at my disposition, of which 25 were vaccinated, and the 

 remaining 25 underwent no treatment. A fortnight after- 

 wards the 50 sheep were inoculated with the most virulent 

 anthracoid microbe. The 25 vaccinated sheep resisted the 

 infection ; the 25 unvaccinated died of splenic fever within 50 

 hours. Since that time the capabilities of my laboratory have 

 been inadequate to meet the demands of farmers for supplies 

 of this vaccine.^ In the space of fifteen days we have vacci- 

 nated in the departments surrounding Paris more than 20,000 

 sheep, and a large number of cattle and horses. This experi- 

 ment was repeated last month at the Ferme de Lambert, near 

 Chartres. It deserves special mention. The very virulent 

 inoculation practised at Pouilly-le-Fort, in order to prove the 

 immunity produced by vaccination, had been effected by the 



* It is matter of regret that the exact methods of preparation used by M. 

 Pasteur in his laboratory are not made public ; so that the present research 

 lias had to be conducted iu ignorance of his details. The fact of his success in 

 producing what he calls a " vaccine " — a something which when iuoculated 

 into sheep produces some modiCed splenic fever that protects the sheep against 

 the after-production of fatal splenic fever when the virulent material is iuocu- 

 lated into the sheep — may be taken as established. 



