VITALITY OF DISEASE GERMS. 49 



drops of hydrocyanic acid, a little strychnia, or 

 the fraction of a grain of nicotina. 



Then there are the marvellous but familiar 

 facts in connection with contagious, self-pro- 

 pagating diseases." Is the poisoned dissecting 

 wound a mere chemical or mechanico-chemical 

 phenomenon ? To what chemical actions does 

 it exhibit the slightest analogy ? and who feels 

 satisfied when he is told that the speck of 

 vaccine lymph is but a bit of albumen in a state 

 of rapid chemical change, which induces che- 

 mical change in the fluids and tissues of the 

 body ? This sort of phrase is often advanced 

 in place of explanation, but not one of the 

 terms of the proposition has any intelligible 

 meaning attached to it. The whole question 

 is begged, and it is expected that the inquirer 

 will be silenced by the learned words which, in 

 his innocence, he may fancy must have some 

 deep or mysterious meaning that his poor in- 

 telligence does not comprehend, or his too 

 scanty knowledge enable him to interpret. Can 

 the changes in one of the little mucus corpuscles 

 from the mucus of the throat be explained by 

 physics, or the movements of the white blood 

 * See " Disease Germs, their Real Nature," 187 1. 



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