IOO 



produces only a very circumscribed, local irritation that 

 does not affect the general health in the least. One or 

 a dozen germs of this fatal disease may be introduced in 

 the tissues and are unable to produce any effect what- 

 ever. Twenty, fifty, or a hundred, according to the sus- 

 ceptibility of the fowl, will produce a slight local irrita- 

 tion. Pasteur's method requires five to nine months to 

 attenuate the virus ; by mine it is accomplished in as 

 many minutes." 



The effect can be secured, therefore, by simple dilution 

 of anthrax or chicken cholera virus, as well as by Pas- 

 teur's cultures, and there are other reasons for suspect- 

 ing that his mysterious method for the mitigation of bac- 

 terial virulence is practically a dilution of the culture, or 

 rather, of the contained bacteria. If Pasteur would 

 demonstrate that his tamed bacilli transmit their tame- 

 ness to subsequent generations, the question would be 

 finally settled ; he asserts, indeed, that he has observed 

 such transmission "in a few cultures." but gives no par- 

 ticulars, while the extensive vaccinations already per- 

 formed on sheep prove that even his first (weak) vaccin 

 sometimes kills an animal. It is but just to state that 

 Koch has recently expressed his conviction that a gen- 

 uine physiological modification does occur in Pasteur's 

 cultures ; whether this conviction is based upon personal 

 observation or not does not appear. 1 



Although proper functional activity may doubtless de- 

 crease susceptibility to infectious diseases, whether of 

 bacterial or of still unelucidated origin, it is evident in 

 our daily observation that such activity does not neces- 

 sarily confer immunity. At present but two avenues to 

 such acquisition are known, a natural attack, and the 

 artificial induction of the disease in mitigated form. The 

 immunity secured by one attack of variola, scarlatina, 

 measles, whooping-cough, etc., and by artificial inocula- 

 tion with variola, as was formerly extensively practised, 



1 1 have not succeeded in procuring Koch's monograph ; the above statement is 

 taken from reviews of it in French and German journals, the Deutsche Med. 

 Wochenschrift, and the Revue Scietitifique, especially. 



