420 



keeiier dust is something to be foiiglit constantly; tlie merchant looks upon 

 it as something that spoils his goods ; the physician looks upon it in the 

 light of a producer of ill health and disease. In industrial cities factory 

 dusts of many kinds occur and produce so-called industrial diseases. 



A very pernicious kind of dust to which people living massed together 

 are exposed is dust containing dried spittle and full of all sorts of in- 

 fective matter, infective dust. This is the kind of dust of most importance 

 to the student of Coniosis. 



The modern dust problem can be considered from many viewpoints, 

 physical, mechanical, economic, sociologic, esthetic, medical, pathologic, 

 biologic. 



Biology and pathology are closely related, often it is difficult to de- 

 termine what is normal and what is abnormal, or what must be considered 

 normal in the light of an abnormal environment. Dusty air produces 

 reactions, states or conditions, in living organisms. Is the change adapta- 

 tive and biological? Is it degenerative and pathological? We expect a 

 tree to grow in the woods but not in the crowded city ; we expect children 

 to grow in the country — but many of us doubt their thriving in crowded 

 cities. We ask what is abnormal, the child that does not thrive or the 

 environment. 



Disease, 111 Health, Symptoms, Reactions to Environment. — Disease 

 is a term loosely applied to all sorts of conditions, to all sorts of reac- 

 tions of the human body (not to speak of animals and plants), on the 

 one hand to the morbid processes induced by the great epidemic diseases 

 that kill by the thousands, and, on the other, to mere feelings of discom- 

 fort as those attendant on overeating, over-exercising, worry, etc., etc. 

 Symptoms and disease and stales of ill health are constantly confused, 

 and indeed are often vei'y confusing. 



Shall the reaction due to inhaling dust be regarded as a disease or as 

 a condition of ill health, or as a reaction to an abnormal or unsanitary 

 environment? Shall we regard the effects pnxluced on inhaling dusty air 

 as a disease, or as a reaction that can be studied in the light of biology? 

 (In answer I may say that several years ago I looked uikhi the reaction 

 as a disease and jtublished a paper based on data then at hand.) 



In this paper I shall consider the subject in the light of a reaction to 

 an abnormal environment, as a problem in biology. I shall consider symp- 

 toms as warnings from nature. If the warnings are heeded man lives on 

 and on; if he does not heed them he perishes. In proportion as man 



