278 PROTECTIVE INOCULATIONS. 



that described by Cliauveau, in 1885. Tliis consists in cultivating the 

 bacillus at a temperature of 38 to 39 C., under a pressure of eight 

 atmospheres. Cultures treated in this way killed guinea-pigs, but 

 did not kill sheep, cattle, or horses, and constituted a suitable atten- 

 uated virus for protective inoculations in these animals. One drop 

 was used for a sheep, and two drops for a cow or a horse, and the 

 immunity was proved to last for a year. 



Kitt, in experiments made in 1884 and 1885, found that an atten- 

 uation of the virulence of anthrax bacilli may be effected by passing 

 them through birds, which have but little susceptibility to anthrax 

 infection; but the results obtained were not uniform, and the method 

 was not thought to have any great practical value. In the same paper 

 Kitt gives an account of his experiments with Pasteur's vaccine, No. 

 1 and No. 2, which he obtained from the agent in Paris. These ex- 

 periments led him to the conclusion that the attenuated cultures used 

 by Pasteur are too weak. But by passing them through guinea-pigs 

 their virulence was increased so that they served to protect cattle and 

 sheep, although not without danger for the last-mentioned animals. 



During the year 1882 Pasteur's method was extensively practised 

 in the department of Eure-et-Loir, where anthrax was very prevalent 

 and had been the cause of extensive losses. The results of these pro- 

 tective inoculations were reported to the Academy of Sciences (seance 

 of December 18th, 1882) by Pasteur, who submitted, with some re- 

 marks, a report prepared by M. Boutet, from which we quote as 

 follows : 



"The number of sheep vaccinated during 1 the year has been 79,392; 

 among 1 these flocks the average annual loss during 1 the past ten years was 

 7,237 9.01 percent. Since the vaccinations but 518 animals have died 0.65 

 per cent. We must observe that this year, probably 011 account of the great 

 humidity, the mortality in Eure-et-Loir has only been three per cent. The 

 losses should therefore have been 2,382, instead of 518, without the vaccina- 

 tions. In the flocks which were only partly vaccinated we had 2,308 vacci- 

 nated and 1,659 not vaccinated ; the loss among 1 the first was 8, or 0.4 per 

 cent.; among 1 the second the loss was 60, or 3.9 per cent. We call attention 

 to the fact that in these flocks, in different cantons of the department, the 

 sheep vaccinated and not vaccinated were subjected to the same conditions 

 of soil, of lodging, of food, of temperature, and that consequently they were 

 exposed to identical influences. 



"The veterinary surgeons in Eure-et-Loir have vaccinated 4,562 animals 

 of the bovine species. Out of this number the annual loss had been 322. 

 Since the vaccinations only 11 cows have died. That is, the annual mortality 

 has been reduced from 7.03 per cent, to 0.24 per cent. 



" Some engorgements, generally not serious, having occurred after vacci- 

 nating 1 horses, and the mortality not being 1 great in this species, the veterina- 

 rians have thought it prudent not to vaccinate horses 011 a large scale. Only 

 524 were vaccinated ; three of these died after the first vaccination." 



Notwithstanding this favorable report some bacteriologists, and 



