YELLOW FEVER 217 



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 glycerine 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 two days dried is used. The mortality 

 from rabies has been greatly reduced by this method 

 of active immunization. At present there is no very 

 accurate laboratory diagnostic test in rabies. The 

 development of the symptoms must be awaited to 

 make the diagnosis in people bitten by rabid animals. 

 The ordinary disinfecting dressings of bichloride of 

 mercury and carbolic acid solutions are worthless for 

 the bites of rabid animals. It is necessary to use 

 the actual cautery or fuming nitric acid in order to 

 certainly remove rabies virus from a wound. 



Yellow Fever. This is an acute infectious disease 

 chiefly of tropical countries, characterized by great 

 prostration, severe pains, hemorrhages, and jaundice. 

 The cause is not known. The disease is transmitted 

 by the mosquito called Stegomyia calopus, which takes 

 some of the infective blood from a patient and trans- 

 mits it to another person. Some cycle of development 

 of the virus takes place in the mosquito because the 



