784 PASTEUR. 



This pioneer work led to further investigations with reference to the 

 cause and prevention of certain infectious diseases of the lower animals, 

 and especially to the fatal disease of cattle and sheep known as anthrax. 

 Having satisfied himself that this disease is due to a bacillus, which is 

 found in great numbers in the blood of infected animals, he demon- 

 strated by experiment that this bacillus rapidly loses its virulence when 

 cultivated in artificial media at a temperature of 42° to 43° 0. Also 

 that animals inoculated with this " attenuated " virus suffer a mild 

 attack of the disease, and that after their recovery they are immune 

 against future attacks, even when inoculated with the most virulent 

 material. This discovery has been applied practically, on an extensive 

 scale, in France, Austria, Switzerland, and other European countries. 

 The result of anthrax inoculations made by Pasteur's method in France 

 during the past twelve years was summarized by Chamberland in 1894. 

 He reports the total number of animals inoculated during this period 

 as 1,788,677 sheep, and 200,962 cattle, and estimates the total saving 

 as the result of the inoculations as 5,000,000 francs for sheep and 

 2,000,000 francs for cattle. 



Another infectious disease in which Pasteur's method has been 

 employed with success is rouget or hog erysipelas. Chamberland states 

 that as a result of the protective inoculations practiced with Pasteur's 

 vaccines the mortality from this disease in France has been reduced 

 from about 20 to 1.45 per cent. Hutyra reports that during a single 

 year (1889) 48,637 pigs were inoculated with Pasteur's vaccines in 

 Hungary with a loss of 0.29 per cent, while the losses upon the same 

 farms in previous years averaged from 10 to 30 per cent. 



But we must pass to that portion of Pasteur's scientific work which 

 has most engaged the attention of the public. Pasteur first announced 

 his success in reproducing hydrophobia in susceptible animals by inocu- 

 lations of material obtained from the central nervous system in a com- 

 munication made to the Academy of Sciences on May 30, 1880. Con- 

 tinuing his investigations he reported, in 1884, his success in conferring 

 immunity against hydrophobia in nineteen dogs inoculated, in the pres- 

 ence of a commission appointed for the purpose, as a test experiment. 

 These animals had been rendered refractory by his method. The nine- 

 teen protected animals and nineteen control animals obtained from the 

 public pound without any selection were tested at the same time. The 

 test was made upon some of the animals of both series by inoculation 

 with virulent material upon the surface of the brain, and upon others 

 by allowing them to be bitten by rabid dogs, and upon still others by 

 intravenous inoculations. JSTot one of the protected animals developed 

 hydrophobia j on the other hand, three of the control animals out of 

 six bitten by a mad dog developed the disease, five out of seven which 

 received intravenous inoculations died of rabies, and five which were 

 trephined and inoculated on the surface of the brain died of the same 

 disease. 



