CONTROL WITHIN THE HOUSE 77 



shutters, or of many kinds of screens, although the 

 apertures thereof may allow of ample room for flies to 

 pass to and fro. If, however, there be windows on 

 two sides of a room, then Venetian blinds and the like 

 will be useless, and window screens must have very 

 close meshes to be effective. The house-fly will pass 

 through netting only when there is light shining on the 

 further side. A knowledge of this fact is very important 

 in the planning of hospital wards. In a sick room, if 

 there be windows on two sides, one in summer time 

 should be darkened when the other is open for 

 ventilation. 



The protection of the larder and the screening of 

 food should never be neglected, but what is of even 

 greater importance is the prevention of access by flies 

 to faecal matter, or to purulent and all unhealthy dis- 

 charges from the sick room. 



