THE BIOLOGY OF THE SEASONS 



duces brilliant butterflies and brilliant beetles." Darwin 

 went the length of saying : " If insects had never existed on 

 the face of the earth, our plants would never have been 

 decked with beautiful colours.'* 



Let us state the thesis more fully. Although many 

 flowers seem able to fall back on self-pollination, it is of 

 advantage to most that insects should visit them. Those 

 most visited are most certainly fertilised ; they produce 

 larger and more vigorous crops of seeds than those of the 

 same kind which have been little visited. Long ago some of 

 the primitive flowers began to form pigments as by-products 

 or waste- products of their everyday metabolism. Those that 

 varied in the direction of conspicuous or attractive colora- 

 tion were most visited, therefore most effectively fertilised, 

 and therefore most prolific in their multiplication. The 

 uncoloured or dully coloured were less likely to be visited, and 

 they would tend to go to the wall. In the case of each kind 

 of flower that was visited by insects attracted by colour, 

 there would thus tend to be a survival of the gay and an 

 elimination of the dull. When we keep the insects in their 

 proper place as the selectors of the variations which the plant 

 afforded, the thesis appears more reasonable. 



If we are convinced that pigments are natural expressions 

 of the normal up-building and down-breaking of the plant, 

 if we can find physiological reasons why they should occur 

 (chloropyll apart) more particularly in connection with the 

 flower, and if we do not find any reason for regarding con- 

 spicuousness of colouring as disadvantageous, then, it seems 

 to us, we can keep insects in their place as selectors, and give 

 flowers some credit for their own beauty. 



In regard to the attractive power of floral colour, there is, 

 to say the least, a need for cautiousness of statement. It 

 has been repeatedly observed that bees do not seem to care 

 much for yellow flowers, that they prefer blue-violet to any 



