166 Professor Tyndall [Jan. 16, 



abroad among the sheep and cattle dealers of France that he had 

 overcome this contagium. In various districts of France the disorder 

 was very deadly. He confined himself for a time, to what might be 

 called laboratory experiments ; but believing that a principle which 

 had proved true in small things would also prove true in large, he had 

 the boldness to accept an invitation from the President of the 

 Agricultural Society of Melun, to make an experiment publicly, on 

 what might be called an agricultural scale. 



He had placed at his disposal a flock of sheep which he divided 

 into two groups. The members of one group were all vaccinated with 

 the " attenuated " virus of splenic fever, while the members of the 

 other group were left un vaccinated. A number of cows were similarly 

 treated. The question to be decided was : Would the mild virus act 

 as a protection ? Experiment alone could answer this question. 

 Fourteen days subsequent to the first inoculation, all the sheep and 

 all the cows, vaccinated and unvaccinated, were inoculated with a 

 highly virulent virus. Three days afterwards, more than two hundred 

 persons, including among them journalists, farmers, lawyers, and 

 public men, assembled to witness the result. Pasteur is capable of 

 elation, and he must have felt elated at the shout of admiration which 

 hailed the success of his exiDeriment. Of 25 sheep inoculated with a 

 virulent virus, but unprotected by vaccination, 21 were already dead, 

 while the remaining 4 were dying. The 25 vaccinated sheep, which 

 had also received the deadly virus into their blood, were in full 

 health and gaiety. The unvaccinated cows showed tumours at the 

 place of inoculation, and were so prostrate with fever as to be unable 

 to eat. The vaccinated cows remained perfectly well, showing neither 

 tumours nor fever, nor even any rise of temperature, and consumed 

 their food with appetites unimpaired. Pasteur was soon overwhelmed 

 with applications for this " benign vaccine." At the end of 1881, 

 close upon 34,000 animals had been vaccinated, while in 1883 the 

 number rose to nearly 500,000. 



Malignant pustule is a very loathsome disease, and the sufferings 

 of animals dying from it are obviously very great. An account of the 

 symptoms which precede death would be by no means pleasant read- 

 ing. Imagine then one of those tender-hearted gentlemen who write 

 about torture and cruelty in the Times, entering the laboratory of 

 Pasteur and seeing him sow this malady among his unprotected 

 victims! Some years ago, accompanied by my wife, I visited the 

 laboratory of the Ecole Normale, and we were shown there by Pasteur 

 himself, the formidable organism in the investigation of which he was 

 then engaged. It was curious to reflect how a thing so mean could 

 exercise such deadly power over man and brute. Both Pasteur and 

 his assistants had to be very wary in dealing with this organism, for 

 either the adult bacillus, or one of its spores, entering the blood by 

 tlie sliglitest scratch on the skin, would have proved fatal to the 

 individual infected by it. In a room adjacent to the laboratory stood 

 a large cage, containing guinea-pigs and rabbits, some sprightly, and 



