^20 



keei)er dust is something: to be fought constantly; the merchant looks upon 

 it as something tliat spoils liis goods; tlio pliysician looks upon it in the 

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

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



A very pernicious kind of dust to wliich 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, sociologies esthetic, medical, pathologic, 

 biologic. 



Biology and pathology are closely related, often it is dithcult 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 thi'iving in crowded, 

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

 environment. 



Disease, 111 Health, Symptoms, Keactions 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 disease* 

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

 fcu't as those attendant on overeating, over-exercising, worry, etc., etc.) 

 Symptoms and disease and states of ill health are constantly confusedJ 

 and indeed are often very confusing. 



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

 a condition of ill health, or as a i-eaction to an abnormal or unsanitary] 

 environment? Shall we regard the etTects produced on inhaling dusty al 

 as a disease, or as a reaction that can be studied in tlu> light of biology' 

 (In answer I may say that several years agti I lodked upon the reactioi: 

 as a disease and published a impel- based on d;ita then at liand.1 



Tn this \):\\ti'\- 1 shiill consider the subject in the liglit of a reaction tC 

 an abnoi'nial environment, as a pi'niileni in iiiology. I shall consider sympij 

 toms as warnings from nature. If the warnings are hee<h'd man lives 01 

 iiiid on; if he does not heed them he iierishes. In iiroiiortion as ma: 



