238 DtrST AND WATER. 



The speaker here read from Dr. Prudden's book: 

 "Dust and its Dangers," passages descriptive of the 

 safeguards with which nature has provided the human 

 body against the inhalation of dust, and also the means 

 for its elimination. All this, however, refers to the dis- 

 position of the inorganic matter which under the general 

 form of dust, may be inhaled. 



The living germs with which we have seen dust is 

 generally laden, are for the most part harmless to the 

 human organism. They are destroyed by the digestive 

 fluids, or they perish for lack of nutriment. 



Here again nature has fortified us with the weapons 

 of effective defence ; but there are germs which, under 

 certain conditions, find in the human organism a place 

 where they may develop and become the propagators of 

 most dangerous disease. That these germs or bacteria, 

 by which name they are now known, are scattered with 

 the dust which we are apt to inhale in public places, and 

 even in the streets, is a fact too well established. The 

 study of bacteriology which has occupied the attention of 

 the scientific physicians during recent years, has developed 

 the fact that every infectious disease is caused by the 

 agency of some form of bacteria. This knowledge has al- 

 ready been of great service to mankind in preventing the 

 spread of infectious disease, and doubtless if, by some 

 wide-spread scheme of co-operation, every one of such 

 cases of disease could be isolated and the bacteria de- 

 stroyed, by fire and disinfection, those diseases might be 

 expected to disappear from the face of the earth. This, of 

 course, cannot be accomplished, but each locality can do 

 much in reducing the danger from this source to the mini- 

 mum. So long, however, as people are indifferent, careless 

 and ignorant, these minute organisms, visible only to the 

 eye of the skilled microscopist, will continue to mingle 

 with the dust which whirls through our thoroughfares, and 

 become the veritable pestilence which walketh in darkness. 



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