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, typhoid-fever, Asiatic cholera, 

 erysipelas, some forms of blood-poisoning, and 

 diphtheria. 



Concerning the kinds of germs which cause 

 many other of the infectious diseases we are 

 yet in doubt. We have an increasing convic- 

 tion that they are 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 

 consideration of the relationship of dust to 

 disease largely to that one bacterial malady 

 which is most important and which we know 

 most about and which we can do most to pre- 

 vent, namely, consumption or tuberculosis. 



