110 UTILIZATION OP MINUTE LIFE. 



Nothing would be easier than to select a portion 

 of some silkworm establishment for the experiment, 

 and to furnish this section of the building with 

 violet-coloured windows. It would indeed be in- 

 teresting to see these w'o?e-coloured panes become 

 as necessary to the silk breeders as the yellow win- 

 dow is essential to the photographer. In the former 

 instance the violet would serve to allow the chemical 

 rays of light to pass, while the other rays are 

 excluded. In the latter, the yellow is used to cut 

 off these chemical rays, and to let pass the re- 

 mainder. 



