DUST AND DISEASE. 327 



may if he has any tiling to say of these diseases which is 

 characteristic of them he cannot evade the use of these 

 terms or the exact equivalents of them. While perfectly 

 applicable to life and to living things, these terms express 

 qualities which are not only inapplicable to common chemi- 

 cal agents, but, as far as I can see, actually inconceivable 

 of them." 



