426 



but preveutable. Proper veutilatiou prevents much ill health — but if the 

 individual asks for it he is apt to be discharged. 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 

 others. The latter are also called 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 health, and of course of disease. Indeed, some dis- 

 eases are said to be made up of symptom-complexes or syndromes and are 

 diagnosed thereby. 



Symptom.s are evidences of abnormal functioning. Symptoms can be 

 regarded as warnings tluit sojuething 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 inhalliig dusty air. 



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

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

 and ecology may be of advantage. 



Symptoms in great variety occur in Coniosis. Many of the common 

 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 common in tlie respiratory type; headache is common in the 

 nervous type; albumiuviria, arrythmia, edema, palpitation in the cardio- 

 vascular, etc. I am here, making only brief references. Symptoms enable 

 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; 

 Ihe place of residence, whether city or country; the 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 month off when not feeling well; etc., etc. The very susceptible indi- 

 vidual may really suffer less by living within limitations than the less sus- 

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

 can largely guard himself against environmental influences but less against 

 hereditary tendencies. 



Some individuals who react acutely are constantly watching them- 

 selves, are "exceedingly careful," and yet if they do not know where the 



