56 DUST AND ITS DANGERS. 



exist. The particular species causing some of 

 these diseases have been isolated and studied 

 and experimented upon in so many ways and 

 by so many workers that we feel perfectly cer- 

 tain about them. Among such diseases are : 

 consumption, pneumonia, typhoid-fever, Asia- 

 tic cholera, influenza, some forms of blood- 

 poisoning, diphtheria, and many "colds." 



Concerning the kinds of germs which cause 

 some other of the infectious diseases we are 

 yet in doubt. They are no doubt also caused 

 by some form of micro-organism or germ, but 

 what it may be and -how it acts is not fully 

 determined. 



Among those infectious diseases the exact 

 causes of which have not yet been made out 

 may be mentioned small-pox, yellow-fever, 

 measles, and scarlatina. 



Now to make a long story short, and to give 

 precision to our theme, I purpose to limit this 

 study of the relationship of dust to disease 

 largely to that one bacterial malady which is 

 most important, which we know much about 

 and which we can do most to prevent, namely, 

 consumption or tuberculosis. 



