DUST AND DISEASE. 43 



the most violent opponent of the germ theory, and, ten 

 to one, you will find them full of such terms as " pro- 

 pagation," ^' self- propagation," ^'•reproduction," "self- 

 multiplication," and so on. Try as he may — if he has 

 anything to say of those diseases which is characteristic 

 of them — he cannot evade the use of these terms, or the 

 exact equivalents to them. While perfectly applicable 

 to living things, these terms express qualities which 

 are not only inapplicable to common chemical agents, 

 but, as far as I can see, actually inconceivable of 

 them.' 



