14 



FLIES AND COLOURS. 



[chap. 



honey on glass slips placed over paper of other colours, 

 yellow, orange, red, green, black, and white. Then I 

 continually transposed the coloured paper, leaving 

 the honey on the same spots ; but the bee always 

 flew to the blue paper, wherever it might be. Bees 

 appear fortunately to prefer the same colours as we 

 do. On the contrary, flowers of a livid yellow, or 

 fleshy colour are most attractive to flies ; and more- 

 over while bees are attracted by odours which are 

 also agreeable to us, flies, as might naturally be 



Fig. 7. — Malva sylvestris. 



Fig. 8. — Mutva rotundtfalia. 



expected from the habits of their larvae, prefer some 

 which to us seem anything but pleasant. 



Among other obvious evidences that the beauty 

 of flowers is useful in consequence of its attracting 

 insects, we may adduce those cases in which the 

 transference of the pollen is effected in different man- 

 ners in nearly allied plants, sometimes even in the 

 same genus. 



Thus, as Dr. H. Miiller has pointed out, Malva 



