502 THE LIFE-WORK OF A CHEMIST. 



than does the injection of the saliva. Here then we have one step in 

 advance. The disease is one of the nerve-centers, and therefore it 

 only exhibits itself when the nerve-centers are attacked. And this 

 goes to explain the varying times of incubation which the attack ex- 

 hibits. The virus has to travel up the spinal cord before the symptoms 

 can manifest themselves, and the length of time taken over that jour- 

 ney depends on many circumstances. If this be so, the period of incu- 

 bation must be lessened if the virus is at once introduced into the 

 nerve-centers. This was also proved to be the case, for dogs inoculated 

 under the dura mater invariably became rabid within a period rarely 

 exceeding eighteen days. 



Next came the question, can this virus be weakened, as has been 

 proved possible with the former poisons'? The difficulty in this case 

 was greater, inasmuch as all attempts to isolate or to cultivate the 

 special microbe of rabies outside the animal body had failed. But Pas- 

 teur's energy and foresight overcame this difficulty, and a method wi.s 

 discovered by which this terrible poison can so far be weakened as to 

 lose its virulent character, but yet remain potent enough, like the cases 

 already quoted, to act as a preventive ; and dogs which had thus been 

 inoculated were proved to be so perfectly protected, that they might be 

 bitten with impunity by mad dogs, or inoculated harmlessly with the 

 most powerful rabic virus. 



But yet another step. Would the preventive action of the weakened 

 virus hold good when it is inoculated even after the bite? If so, it 

 might be thus possible to save the lives of persons bitten by mad dogs. 

 Well, experiment has also ]>roved this to be true, for a number of dogs 

 were bitten by mad ones, or were inoculated under the skin with rabic 

 virus; of these some were subjected to the preventive cure and others 

 not thus treated. Of the first or protected series not one became mad; 

 of the other, or unprotected dogs, a large number died with all ihe 

 characteristic symptoms of the disease. But it was one thing to thus 

 experiment upon dogs, and quite another thing, as you may well imag- 

 ine, to subject human beings to so novel and perhaps dangerous a treat- 

 ment. Nevertheless, Pasteur was bold enough to take this necessary 

 step, and by so doing has earned the gratitude of the human race. 



In front of the Pasteur Institute in Paris stands a statue worked 

 with consummate skill in bronze. It represents a French shepherd boy 

 engaged in a death struggle with a uiad dog which had been worrying 

 his sheep. With his bare hands, au<l with no weapon save his wooden 

 sabot, the boy was successful in the combat. He killed the dog, but 

 was horribly bitten in the fight. The group represents no mythical 

 struggle; the actual event took place in October, 1885; and this boy, 

 Jupille, was the second person to undergo the anti-rabic treatment, 

 which proved perfectly successful, for he remained perfectly healthy, 

 and his heroic deed and its consequences have become historic. "Ces^ 

 le premier pas qui coute,''^ and as soon as the first man had been success- 

 fully treated others similarly situated gladly availed themselves of Pas- 



