for the year 1884. xxiii 



in a mild form ; and so purchasing future immunity from the 

 more severe and dreaded forms of the disease. Inoculation 

 with small-pox virus gave way to vaccination, which has 

 now for many years constituted the one great preventive of 

 the spread of small-pox, and the safeguard of the individual 

 against proneness to the disease, and especially to its most 

 virulent forms. The principle of inoculation for inducing 

 mild types of other diseases has been advocated, and, indeed, 

 practised, with more or less success, as was the case with 

 pleuro-pneumonia and anthrax in cattle. Pasteur some 

 time since made a number of experiments on animals, and 

 appears to have proved that some infectious diseases, 

 destructive to fowls, especially chicken-cholera, induced by 

 inoculation, protected the individual from future attacks of 

 the same disease. More recently he carried out a series" of 

 analagous experiments with regard to rabies or hydrophobia 

 in dogs. The results he announced are not only interesting, 

 but, if borne out by future experience, of the utmost im- 

 portance ; not merely as relating to hydrophobia, but in 

 connection with the general question of inoculation with 

 disease poison. The results of Pasteur's investigations, as 

 given by himself, are that dogs inoculated with rabies poison 

 get the disease in a fatal form ; that if a monkey is inoculated 

 with the virus from a mad dog it contracts the disease, but 

 in a milder form ; if a second monkey is inoculated with 

 the poison from the first it takes the disease still more 

 mildly, till after the third removal from the dog through 

 monkeys the virus becomes so far attenuated as to induce 

 hydrophobia in a very mild and non-fatal form, and dogs so 

 inoculated remain protected against the further virulent 

 poison of a bite from a rabid dog. M. Pasteur states he 

 found that if instead of monkeys he used rabbits or guinea 

 pigs for successive inoculations, the virus appeared to be so 

 intensified, rather than diluted, that dogs inoculated at the 

 third removal took the disease with greater virulence than 

 if the poison used had been taken from an ordinary rabid 

 dog. Should these results be confirmed it opens up a most 



