THE STORY OF NINETEENTH-CENTURY SCIENCE 



drove of fifty sheep, half of which were to be inoculated 

 with the attenuated virus by Pasteur. Subsequently all 

 the sheep were to be inoculated with virulent virus, all 

 being kept together in one pen, under precisely the same 

 conditions. The "protected" sheep were to remain 

 healthy ; the unprotected ones to die of anthrax ; so 

 read the terms of the proposition. Pasteur accepted 

 the challenge ; he even permitted a change in the pro- 

 gramme by which two goats were substituted for two 

 of the sheep, and ten cattle added ; stipulating, however, 

 that since his experiments had not yet been extended to 

 cattle, these should not be regarded as falling rigidly 

 within the terms of the test. 



It was a test to try the soul of any man, for all the 

 world looked on askance, prepared to deride the maker 

 of so preposterous a claim as soon as his claim should be 

 proved baseless. Not even the fame of Pasteur could 

 make the public at large, lay or scientific, believe in the 

 possibility of what he proposed to accomplish. There 

 was time for all the world to be informed of the proced- 

 ure, for the first "preventive" inoculation, or vaccina- 

 tion, as Pasteur termed it, was made on the 5th of May, 

 the second on the 17th; and another interval of two 

 weeks must elapse before the final inoculations with the 

 unattenuated virus. Twenty-four sheep, one goat, and 

 five cattle were submitted to the preliminary vaccina- 

 tions. Then, on the 31st of May, all sixty of the ani- 

 mals were inoculated, a protected and an unprotected 

 one alternately, with an extremely virulent culture of 

 anthrax microbes that had been in Pasteur's laboratory 

 since 187T. This accomplished, the animals were left 

 together in one enclosure, to await the issue. 



Two days later, the 2d of June, at the appointed hour 



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