124 PASTEUR 



has so far vanished that, if an emulsion of the cord be 

 injected, it produces no rabies, but has only a slight 

 vaccinating effect. If two days later an emulsion of a 

 twelve-days-old spinal cord be injected, the vaccinating 

 effect is stronger; but the body, already inured to 

 slight doses of the poison, remains unaffected. Thus, 

 by gradually increasing the strength of the dose, a 

 virus may at length be injected which would infallibly 

 produce rabies but for the previous inoculations. 

 When an animal is bitten by a mad dog, the poison 

 transmitted takes some time to develop — some weeks 

 at least, and often many months. If now the artificially 

 introduced virus ' gets the start,' so to speak, of the 

 naturally introduced poison, by the time the latter is 

 at its height the animal has become gradually im- 

 munified to the specific poison and suffers Httle 

 harm. The arsenic -eaters of the Tyrol afford an 

 analogous case. They consume amounts of arsenic 

 which would infallibly produce peripheral neuritis in 

 men unaccustomed to such a diet. 



It needed no small courage on Pasteur's part to in- 

 oculate his fellow-creatures against hydrophobia. In 

 1885 a boy some nine years old, from Meissengott in 

 Alsace, was brought by his mother to the laboratory 

 suffering from fourteen wounds inflicted by a mad dog. 

 After long consultations with his assistants and the 

 most anxious deliberations, he consented to the in- 

 oculation of the boy. The next fortnight was a time 

 of intense anxiety, but all went well. His second 

 patient is commemorated by the bronze statue which 

 ornaments the front of the Pasteur Institute in Paris. 

 It represents the struggle between a peasant boy 

 armed only with his sabot, and a mad dog; the boy 

 was terribly bitten, but the treatment saved his life. 

 It is not easy to arrive at an accurate estimate of the 

 death-rate caused by rabies ; but the most careful and 

 moderate estimates show that, before this treatment 



