I SO MANUAL OF BACTERIOLOGY. 



to be any question as to its efficiency. Laboratories where 

 Pasteur's method of treatment is used now exist in all parts 

 of the world. According to statistics collected by Ravenel, 

 based on many thousands of cases, the mortality from rabies 

 in those so treated is less than one per cent. 1 



Antitoxins. The first efforts to point out the way along 

 which antitoxins might be secured were made by Salmon 

 and Smith in 1886. In their experiments pigeons were in- 

 jected with filtrates from cultures containing the products 

 resulting from growth of the hog-cholera bacillus. Such 

 pigeons were found to be immune to this bacillus, which 

 is pathogenic to ordinary pigeons. 



As was stated in the last chapter, bacterial poisons may be 

 of tw r o sorts. In one group the poisons occur chiefly within 

 the bodies of the bacteria. This group seems to contain the 

 majority of the pathogenic bacteria. Methods of protection 

 against infections caused by them will be considered here- 

 after. In the other group, the poisons do not, for the most 

 part, remain in the bodies of the bacteria, but are readily 

 diffused from them into their surroundings. It is for the 

 bacteria of the latter group that antitoxins have been made. 

 Its most important members are the bacilli of diphtheria and 

 tetanus. Their poisons may be found in the culture-media 

 in which they have grown. The principle employed in pre- 

 paring antitoxins was established by Behring. The bacilli 



l ln cases of dog-bite there is often some doubt as to whether or not 

 the dog was rabid. The dog should be allowed to die under observa- 

 tion. A large ganglion, as that of the pneumogastric nerve, should be 

 removed and placed in absolute alcohol or ten per cent, fcrmaldehyde 

 solution. Microscopic changes have been observed in the ganglia which 

 seem to be quite constant in rabies. See Ravenel and McCarthy, Uni- 

 versity of Pennsylvania Medical Bulletin, June, 1901 ; also editorial in 

 Philadelphia Medical Journal, March 14, 1903. The diagnosis may be 

 made by inoculating a rabbit as above described, but the results are not 

 obtained quickly enough to be of value. See V. A. Moore, ''Infectious 

 Diseases of Animals." 



