96 DUST AND ITS DANGERS. 



the favorable combination of conditions occur, 

 but and let this be noted well the nows and 

 agains are frequent enough in the aggregate to 

 secure for consumption the distinction of being 

 the most common and serious, as it is the most 

 distinctly preventable, disease known to man. 



It might be thought that if we know what 

 form of germ causes a given infectious disease, 

 and what chemical substance or drug will kill 

 it, we could readily control the disease when 

 once established in the body by giving a medi- 

 cine which would kill the germs. So we could ; 

 but unfortunately the whole body is made 

 up of little masses of living matter, which 

 we call cells, and these are about as readily 

 killed as bacteria are by the drugs which we 

 should like to use for this purpose. So that in 

 killing the germs we should be apt to stop the 

 disease indeed, but kill the body too. 



We hope sometime, as has been already 

 said, to find some sort of agency which will 

 kill, or render harmless, the germs which cause 

 infectious diseases without harming the body. 

 But in the meanwhile, and perhaps always 

 since the Irishman's conduct in swallowing 



