4i 6 Hydrophobia, Lyssa, or Rabies 



" fixed virus " by inoculating other rabbits, and after the 

 virus has become " fixed " are also used for treating the 

 bitten patient. 



For this purpose, however, Pasteur attenuated the virus 

 by drying the cords, placing them in a bottle containing 

 caustic potash. 



The longer the cord dries, the more the virulence of the 

 micro-organisms attenuates, and as in beginning the immuni- 



Fig. 130. Method of drying the spinal cord of a rabbit for the purpose of 

 attenuation (Stimson, Bull. No. 65, Hygienic Laboratory). 



zation of human beings it is essential to use very attenuated 

 material, the first cord used to furnish inoculation material 

 must have dried about ten days. 



The cord, when it has reached the necessary attenuation, 

 is transferred, and i cm. of it is emulsified with 3 c.c. of sterile 

 0.8 per cent, salt solution. There can be no absolute ac- 

 curacy of dosage. The injection material made in the 

 laboratory under strict aseptic precautions can be used with 

 perfect safety for many hours subsequently if kept cold, and 



