230 DISEASES OF UNKNOWN ETIOLOGY 



stainable granules in the nerve cells of the brain. 

 These so-called "Negri bodies'.' are demonstrated by 

 special staining methods. When a dog is suspected 

 he is killed and his brain removed. Bits of it are 

 stained for microscopic examination and other pieces 

 are made into an emulsion, which is injected into the 

 brain of a rabbit. If rabies virus be present this sus- 

 ceptible animal will die within three weeks as a rule. 

 Recently attempts at the cultivation of the rabies 

 virus have been rewarded by the development, under 

 anaerobic conditions, of minute globoid bodies with a 

 tiny nucleus and with such cultures animals have been 

 infected. 



Pasteur found a method for protective inoculation 

 treatment against rabies. He found that if the spinal 

 cord of a rabbit suffering from rabies were removed and 

 dried in a vacuum it lost its virulence for other rabbits. 

 If he dried it two weeks nearly all of the virulence was 

 lost, but if only two days, its strength was only slightly 

 impaired. He found that if he inoculated animals 

 with gradually increasing strengths or quantities of 

 emulsions made from these dried rabbits' spinal cords, 

 a certain degree of immunity was obtained. This 

 principle is now used in treating persons bitten by 

 rabid animals. The treatment is possible after the 

 bite and the outlook is better the sooner after infection 

 the treatment is begun. The spinal cords of rabbits 

 are ground up in glycerin and injections are made 

 under the skin. The patient first receives a dose 

 from a cord dried fourteen days, then from one dried 

 twelve or thirteen days, then ten or eleven days, and 

 so on until one dried two days is used. The mortality 



