2o6 The Story of the Bacteria 



places are due to agencies which- the current 

 principles of ventilation almost wholly ignore. 



What science requires to-day is not only 

 plenty of oxygen and not too much carbonic 

 acid, but proper temperature and moisture of 

 the air. If we add to these requirements 

 freedom from floating dust, we shall have set 

 down the least which should satisfy a lover of 

 fresh air in his enforced thralldom to the 

 petty, damaging, and increasing tyrannies of 

 in-doors. 



In dwelling-houses, the problem of ven- 

 tilation is in many respects simpler than in 

 large assembly rooms, because to a certain 

 extent the householder is aware of the possi- 

 bilities of dust infection, from the condition 

 of health of the inmates, and can act accord- 

 ingly. But even here, under ordinary con- 

 ditions, there seems to be, from what we have 

 learned about the bacteria, more reasons than 

 we have before appreciated for securing ade- 

 quate ventilation and cleaning. 



The ordinary practice of occasionally stirring 

 up the settled dust with a feather-duster should 

 give place to the use of moist cloths or dry 



