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parts of the body. Thus inoculations in the tails of cattle 

 proved ineffective, but when the temperature was artificially 

 increased the specific disease developed. These ideas have 

 a bearing upon the greater or less success of vaccinations 

 according to the time of year when they are practised and 

 the surrounding conditions of temperature ; and also upon 

 the appearance of epidemics at particular seasons and in 

 particular years. Finally, with respect to the special 

 relations between the specific microbe and different tissues, 

 it may be mentioned that the special nidus of the virus of 

 rabies appears to be the nerve-centres. 



15. — In regard to all these phenomena, the question of 

 spore formation cannot fail to attract attention, and the re- 

 lation between spore formation and the presence of oxygen 

 might prove a fruitful subject of inquiry. Klein's most in- 

 genious experiments on the cultivation of Bacillus anthracis 

 in gelatine pork tend to show that spores are not formed except 

 in the presence of free oxygen, and in opposition to Pasteur he 

 maintains that anthrax spores are never formed in the bodies 

 of animals. On the other hand Miquel's observations on 

 bacilli in general appear to agree to some extent with Pasteur's 

 opinions. He says: "We may experimentally induce the 

 formation of bacillus spores by depriving the bacilli of oxy- 

 gen, or in determining the slow death of the adult forms by 

 antiseptics, but evidently not by killing them rapidly, as 

 then all vital phenomena cease and spores cannot be formed. 

 The best way in which to obtain bacillus spores rapidly 

 appears to me to be by enclosing nutritive infusions charged 

 with filamentous bacilli in sealed tubes containing very little 

 air." There is much obscurity and contradiction on this point, 

 which may be due to all the conditions not having been duly 

 considered, and it seems to offer a most promising field for 

 investigation. Meanwhile the question arises whether the 

 so-called spores are really the terrible things we are inclined 

 to suppose them. There are some noteworthy phenomena con- 



