THE MICROBES OF ANIMAL DISEASES. 765 



The vaccine thus obtained in Pasteur's laboratory is now distrib- 

 uted throughout the world, and has already saved numerous flocks 

 from almost certain destruction. Although this process has only been 

 known for a few years, its results are such that the gain to agriculture 

 already amounts to many thousands of pounds. 



Toussaint makes use of a slightly different mode of preparing a 

 vaccine virus, which is, however, analogous to that of Pasteur. He 

 subjects the lymph of the blood of a diseased animal to a temperature 

 of 50, and thus transforms it into vaccine. Toussaint considers the 

 high temperature to be the principal agent of attenuation, and ascribes 

 little or no importance to the action of the oxygen in the air. 



Chamberland and Roux have recently made researches with the 

 object of obtaining a similar vaccine by attenuating the primitive 

 virus by means of antiseptic substances. They have ascertained that 

 a solution of carbolic acid of one part in six hundred destroys the mi- 

 crobes of anthrax, while they can live and flourish in a solution of one 

 part in nine hundred, but without producing spores, and their viru- 

 lence is attenuated. When a nourishing broth is added to a solution 

 of one in six hundred, the microbe can live and grow in it for months. 

 Since the chief condition of attenuation consists in the absence of 

 spores, this condition seems to be realized by the culture in a solution 

 of carbolic acid, one in nine hundred, and it is probable that a fresh 

 form of attenuated virus may thus be obtained. Diluted sulphuric 

 acid gives analogous results. However this may be, the vaccine pre- 

 pared by Pasteur's process is the only one which has been largely used, 

 and which has afforded certain results to cattle-breeders. 



Public experiments, performed before commissions composed of 

 most competent men, have clearly shown the virtue of the protective 

 action. In the summer of 1881 the initiation was taken by the Melun 

 Society of Agriculture. Twenty-five sheep and eight cows or oxen 

 were vaccinated at Pouilly-le-Fort, and then reinoculated with blood 

 from animals which had recently died of anthrax, together with 

 twenty-five sheep and five cows which had not been previously vac- 

 cinated. None of the vaccinated animals suffered, while the twenty- 

 five test sheep died within forty-eight hours, and the five cows were 

 so ill that the veterinary surgeons despaired of them for several 

 days. 



This experiment was publicly repeated in September, 1881, by 

 Thuillier, Pasteur's fellow- worker, whose death we have recently had 

 to deplore, before the representatives of the Austro-Hungarian Gov- 

 ernment ; and again near Berlin, in 1882, before the representatives of 

 the German Government, and always with the same success. Up to 

 April, 1882, more than one hundred and thirty thousand sheep and 

 two thousand oxen or cows had been vaccinated ; and since that time 

 the demand for vaccine from Pasteur's laboratory has reached him 

 from every quarter. 



