43^ 



perhaps an intoxication ; the excessive use of condiments ; the influence 

 oi heat or cold, etc. To what extent to spealv of diseases, of symptoms 

 or of reactions is at times a difficult matter to determine, there are no 

 hard and fast lines, no more than between species, subspecies and varieties. 

 Opinions vary. 



What is in dust that produces the condition described as Coniosis? 

 This is really a question for the pathologist and bacteriologist, for men 

 who study causes. For our present purposes all we need to know is that 

 there is something to which the body reacts. In illustration might be 

 mentioned malaria : all we need to linow to protect ourselves from ma- 

 laria is to keep from being bitten by the mosquito which transmits tlu* 

 disease, and indeed we need not fear its bite at all if there is no malaria 

 aliout. We know what the active cause of malaria is but in the case of 

 Yellow Fever transmitted by another species of mosquito we do not know, 

 and yet Iveeping the mosquito under control and avoiding being bitten 

 means to prevent the ravages of Yellow Fever. 



In the case of Coniosis as defined above we need only consider kinds 

 of dust, whether in part it came from man, particularly expectoration 

 and whetlier sterilized by age or sunlight. The inhalation of country 

 dust may be disagreeable but it is not the kind of dust that produces 

 Coniosis. We at once see that infected dust is very common in backward 

 cities, less in clean cities and wholly absent in the isolated country. 



We see an analogy in pollenosls or hay-fever. This occurs where the 

 pollen of certain plants abounds. The hay-fever victim no longer expects 

 to be cured by the use of drugs ; lie knows that he will feel miserable as 

 long as he is exposed to the particular pollen to which he reacts. To get 

 relief, he "changes climate;" he goes where the air is free from tliis irri- 

 tating dust— just as people who are educated regarding Coniosis will also 

 make a change. 



"Precolds" under exposure to "exciting causes" result in "colds." 

 Colds are commonly although not necessarily always attacks of Dust In- 

 fection. 



To what extent the body protects itself and to what extent man 

 makes an effort to protect himself are very practical questions, but they 

 can not be considered in this brief abstract. People are often "exceed- 

 ingly careful" in their attempts to avoid ill health and sickness, but not 



128—29034] 



