BUTTERFLIES 



THE beauty of butterflies is partly due to their 

 shape and proportions and to their very graceful 

 outline, but it is in their colouring that their chief 

 beauty lies ; and concerning this colouring I wish 

 to say a few words, even at the risk of repeating 

 what is already familiar. 



The colour of a butterfly is due to the scales 

 which cover both surfaces of the wings and which 

 are easily rubbed off by our fingers. These scales 

 are of various shapes and overlap each other like 

 the tiles on a roof, each having a short stalk for 

 insertion into a small depression in the wing, 

 Their variety of colour is extraordinarily great and 

 is due partly to actual pigments ; the brightest tints 

 however, and more especially the metallic lines 

 seen in some foreign butterflies, and perhaps best 

 of all in humming-birds, are due to fine lines on the 

 surface of the wings producing what are known to 

 physicists as interference colours. 



Let us consider the question. Why should 



