474 MICROBIOLOGY OF SPECIAL INDUSTRIES. 



pension just under the exposed dura mater. The inoculation of ordinary 

 rabies virus usually produces symptoms of "dumb rabies" and the death 

 of the animal in fourteen to eighteen days. In order to increase the 

 virulent properties of the same strain of rabid material, it is transmitted 

 from rabbit to rabbit by subdural inoculations until the incubation period 

 is shortened to about six days. Experience has shown that when the 

 virus has reached its maximum degree of virulence for the rabbit, the 

 animal shows symptoms on the sixth or seventh day after inoculation 

 When the virus attains this degree of virulence it is called "fixed virus' 

 and may be used in the preparation of the vaccine. The "fixed virus" 

 or spinal cord of rabbits, which have succumbed to the disease in six or 

 seven days, is removed aseptically and placed in a special drying chamber 

 The cords are suspended over caustic potash and dried at a temperature 

 of 23 for a period of from one to ten or fifteen days. 



The treatment of the patient consists in the hypodermatic application 

 of the "fixed virus" which has been attenuated by drying. The exact 

 nature of the vaccine used in the initial vaccination and the time consumed 

 in the series of injections depend, to some extent, upon the case in hand. 

 Frequently, the patient is first vaccinated with a suspension of a spinal 

 cord which has been attenuated by drying for fourteen or fifteen days. 

 On the succeeding days of the treatment use is made of the suspension of 

 spinal cords, which have been less and less attenuated. The treatment 

 usually lasts about twenty days or until the patient has received an 

 injection of the least attenuated "fixed virus." 



It is very important, when one is bitten by a rabid animal, that the 

 Pasteur treatment be begun as early as possible, in order that active 

 immunity may be secured before the expiration of the incubation period. 

 In many of the larger cities of the United States laboratories are main- 

 tained for the purpose of administering the Pasteur treatment. 



Hogyes* substituted dilutions of the "fixed virus" for the dried spinal 

 cords. For the initial treatment, a few cubic centimeters of a one to ten 

 thousand dilution was used. In the succeeding injections graduated 

 dilutions were employed. While the work of Hogyes has been confirmed 

 by other investigators, the method is not generally regarded as possessing 

 the safety of the original Pasteur treatment. 



DORSET-NILES (HOG-CHOLERA) SERUM, f To prepare the material 



* Hogyes: Acad. des Sciences de Buda-Pest, Oct. 17, 1897. 

 j" U. S. Bureau of Animal Industries, Bui. No. 102. 



