HYDROPHOBIA. 



699 



By prolonged centrifugation of an emulsion of 

 infected nervous tissue the overlying fluid loses its 

 infectiousness. 



The possibility that the organism secretes a sol- ioxi 

 uble toxin is important from the standpoint of im- 

 munisation. A number of observers, particularly 

 Babes, and Heller and Bertarelli, noted that fil- 

 trates of infected nervous tissue sometimes cause 

 emaciation, paralyses and eventual death without- 

 producing a disease which is transmissible to other 

 animals. The organism is without doubt toxic, 

 but these results give us no idea of the nature of 

 the toxin. 



The virus of hydrophobia as contained in the 

 central nervous system of infected animals exhib- 

 its strong resistance to chemical germicides. Five 

 per cent, carbolic acid destroys it in fifty minutes, 

 1 per cent, in three hours, and 1-1000 corrosive 

 sublimate in three hours (Marx). It resists the 

 action of putrefactive bacteria, and has been found 

 virulent in animals which had been buried for two 

 to four weeks, even when the brain was putrid. Di- 

 rect sunlight destroys it, however, in a very short 

 time. According to Tizzoni and Bongiovanni, the 

 rays of radium have a destructive action on the 

 virus. It is less resistant to heat, being destroyed in 

 one-half hour at a temperature of 52-58 C. 

 (HogyesX but is not affected by the temperature 

 of liquid air for three months. Chlorin destroys 

 it very rapidly. It is gradually weakened by 

 desiccation, as first shown by Pasteur, the virus 

 probably undergoing gradual death rather than 

 mere attenuation. It is said to be attenuated by 

 the action of the gastric juice and by the bile. 

 When the neryrvi? tissue is emulsified in glycerin, 



Resistance 

 of Virus. 



