Fermentation and Kindred Phenomena. 109 



Pasteur's laboratory is now distributed throughout the world, 

 and has already saved numerous flocks from almost certain 

 extinction."* Pasteur proceeded in a precisely similar manner 

 in preparing a vaccine for fowl cholera — a very fatal disease 

 incidental to poultry. Another method for preparing a vaccine 

 fluid for various diseases, consists, so to speak, in passing the 

 disease in question from one species of animal to another ; the 

 second species (in certain cases) taking only a slight illness, and 

 then becoming protected against the virulent form. " Thus 

 while the bacillus (from the blood) of sheep or cattle dead of 

 anthrax invariably produces death when inoculated into sheep 

 or cattle, after passing through white mice loses its virulence 

 for those animals. The blood of white mice dead of anthrax 

 does not kill sheep, but only produces a transitory illness, and 

 the animals are for a time at least protected against the virulent 

 disease." (Klein.) 



Pasteur, in his now famous experiments on hydrophobia, at 

 first made use of a similar method. He proved first of all that 

 the disease is to a large extent, localised in the nervous system. 

 Thus a healthy dog is very rapidly inoculated by exposing its 

 brain, and then inoculating the surface of that organ with a 

 particle of the brain of a rabid animal. To attenuate the virus 

 he inoculated a rabbit's brain with a morsel of the brain of a 

 mad dog, then passed the disease from the rabbit to a monkey, 

 whence it became attenuated, and a protective vaccine for dogs. 

 His present method is quite different, and consists in inoculating 

 with the crushed spinal cord of a rabbit dead of hydrophobia, 

 the cord being previously exposed to pure air for a certain 

 number of days. 



Antiseptics and Disinfectants. — It has long been known that 

 various chemical substances prevent and arrest putrefaction, and 

 hinder the spread of infectious diseases. In fact, that such was 

 the case was known long before the " germ" theory had been 

 introduced. As soon as it was discovered that putrefaction and 

 infectious diseases are closely allied, and are both caused by 



* Troussart, 



