228 STUDIES IN PHYSIOLOGY 



with the air. After a short time, the room is "dusted," 

 often with a feather duster. The germs which may have 

 settled on the horizontal surfaces are again whisked off into 

 the air. Few, if any of them, are gathered up in the floor 

 dirt, and so the room, so far as bacteria are concerned, is 

 just as dirty as before. Experiments have demonstrated, 

 too, that the number of germs in a room is not materially 

 affected by ventilating currents, unless there is a strong 

 draught. 



All this germ dirt can be removed, however, by the appli- 

 cation of a few common-sense principles. In a room which 

 has not been used for three to four hours, practically all of the 

 germs and fine dust particles have settled out of the air upon 

 the horizontal surfaces. Hence, it is clear that after a room 

 has been swept (and in public halls this should be done at 

 night), a considerable time should elapse before dusting is 

 begun. For dusting a damp cloth should be used; in this way 

 all the particles of dirt are collected and can thus be removed 

 from the room. Were these methods of cleaning adopted, 

 the air we breathe in the rooms which we occupy would be- 

 come practically germ free, and there would be a surprising 

 decrease in the number of colds and other diseases to which 

 the flesh seems to be heir. 1 



Carpets and draperies collect and hold quantities of dust. 

 They should therefore be removed to the open air when 

 being cleaned, otherwise the dust will simply be driven from 

 one part of the room to another. It is much more hygienic 

 to have hard-wood floors covered with rugs. Dirty streets, 

 too, are a constant source of dust infection. Most of the 

 irritation from this source would be avoided, however, if 

 the citizens insisted that the streets be kept watered, 

 especially when they are swept. 



1 See " Dust and its Dangers," by Dr. T. Mitchell Prudden. G. P. 

 Putnam's Sons, New York. 



