THE CONQUEST OF RABIES 1 7 



Thus far Pasteur's discoveries had not saved a single 

 human life, while Jenner's one discovery had saved hun- 

 dreds of thousands. And yet Pasteur had really made 

 a discovery of greater value to mankind than Jenner's. 

 This is true even though smallpox had been one of the 

 worst scourges of the seventeenth and eighteenth centuries, 

 while anthrax was a disease of sheep and cattle rarely 

 attacking human beings. Jenner had made a chance dis- 

 covery and did not know how to apply the same method 

 to the attack of other diseases. Pasteur, on the other 

 hand, had reasoned out the control of anthrax from a 

 theory already in his mind, and since the theory had 

 worked once, there was no reason why it could not work 

 again. And it has ; disease after disease has since yielded 

 to a similar line of attack. The first human disease to be 

 conquered in this way was rabies ; and again it was Pasteur 

 who made the conquest. He is said to have attacked that 

 disease first because of a horror of hydrophobia which had 

 persisted in his mind ever since losing a boyhood friend by 

 this disease following the bite of a rabid wolf. 



He used the same principle to control rabies that he had 

 with anthrax, but his methods had to be different. After 

 experimenting in various ways, he finally discovered that 

 if he -removed the spinal cord of a rabbit dead of this 

 disease, it would cause the disease in another animal ; but 

 if dried under certain conditions for a number of days, the 

 germs in it lost their virulence and yet caused an animal 

 inoculated with them to become partly immune so that 

 fresher material could be used without producing the dis- 

 ease. In this way Pasteur found that an animal could be 

 made immune to rabies. 



