PROTECTIVE INOCULATION 557 



ployed as a prophylactic in swine erysipelas, tetanus, and 

 diphtheria. 



The use of the tetanus antitoxin to immunize horses 

 against tetanus before subjecting them to operations, such as 

 castration, or after receiving punctures of the skin or hoof 

 ("farrier's puncture") is becoming more and more prevalent 

 in those countries and localities where tetanus is common. In 

 France it seems to be used more than elsewhere. The extent 

 to which it is emplo3'ed is indicated by the fact that in 1896 

 there were sent out from the Pasteur Institute of Paris 1,511 

 bottles of ID cc. each of tetanus antitoxin ; in i8g8 the num- 

 ber rose to 24,950 bottles; and in 1900 it exceeded 43,000. 

 The most of this was for the protection of injured animals 

 against tetanus. It is given in two injections from 10 to 12 

 days apart. Large animals receive 20 cc. but small ones from 

 6 to 10 cc. at each injection. 



The value of diphtheria antitoxin as an immunizing agent 

 against diphtheria in children is a well-known fact. 



III. The simultaneous method. This consists in using a 

 strong virus together with an immunizing serum. The pro- 

 cess is of comparatively recent date. It is used quite exten- 

 sively against rinderpest, anthrax, and in rabies. 



In case of rinderpest the animals are injected with a pro- 

 tective serum simultaneously with the virulent blood. The 

 immune serum is obtained from animals that have recovered 

 spontaneously from rinderpest or from cattle that have been 

 immunized by bile or some other method. The serum alone 

 of animals that have recovered spontaneously possesses very 

 slight protective properties unless very large doses are given. 

 Kolle and Turner showed that if animals just recovering from 

 an attack were injected with large quantities of the blood 

 coming from animals suffering with a fatal attack, the pro- 

 tective poWer of their serum was markedly increased. This 

 serum may be kept for a long time by adding a small quantity 

 of carbolic acid. 



In rabies the method is reported to be most successful. 

 Its essential advantage over the other process is that it can be 



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