426 



but preveutiible. I'l-uiier veiitilatiuu prevents much ill health — but if the 

 individual asks for it he is apt to be discluirged. We here see the value 

 of Unions in making a combined demand. 



Symptoms. — Symptoms are usually divided into subjective and ob- 

 jective, those that we experience ourselves and those that we observe in 

 other.s. The hitter are also calle<l signs. Some signs are discoverable 

 only by the use of instruments, or laboratory methods. 



Ordinarily we do not speak of symptoms of health, but we do speak 

 of symptoms of ill liealtli, and of course of disease. Indeed, some dis- 

 eases are said to be made ui,> of symptom-complexes or syndromes and are 

 diagnosed thereby'. 



.Symptoms are evidences of abnormal functioning. Symptoms can be 

 regarded as warnings that something is wrong. In this volume I am 

 speaking of symptoms not as evidences of the presence of disease but as 

 an evidence of a reaction due to inhaling dusty air. 



The individual who does not react to his environment is exceptional. 

 At the other extreme are the very susceptible, to these a study of mesology 

 and ecology may be of advantage. 



Symptoms in great variety occur in Coniosis. IMany of the connuon 

 ones accompany the general type, others are more or less limited to the 

 special types. Pain, in its widest sense, is a very common symptom. 

 Cough is connnon in the respiratory type; headache is conunon in the 

 nervous type; albuminuria, an-ytliniia, edema, palpitation in the cardio- 

 vascular, etc. I am here making (inly brief references. Symptoms emiblo 

 us to classify or group. 



SuscEPTiBiLiTy. — This varies greatly and is determined by a large num- 

 ber of factors, such as the phylogenetic history ; the ontogenetic history ; 

 the place of residence, whether city or country; tlie amount and intensity 

 of the exposure; the air conditions before and after exposure; the state 

 of nutrition, whether over- or underfed ; the ability to take a day, a week 

 or a montii otf when not tceling well; etc., etc. The very suscei)tible indi- 

 vidual may really sulfi'r less by living within limitations than the less sus- 

 ceptible who is heedless. It needs scarcely be added that an individual 

 can largely u'liard hiniseir against envii-onniciilal iiilluenccs but less against 

 heivditary tendencies. 



Some individuals who read acutely are constantly watching theni- 

 srlves, arc "exceedingly carcfnl,'" and yet if llicy do not laiow where the 



