242 NATURAL SCIENCE [October 1898- 



increased brilliancy has been of advantage. But the bees for whose 

 favours the plants were bidding would have ruined all, had not the 

 plants on their side had a very marked characteristic : infertility 

 with varieties of the same species, or with other species of the same 

 genus. The bees have constancy enough to ensure frequent cross- 

 fertilisation between plant and plant within one variety or species r 

 but, intent upon their own business, they take no trouble to put 

 barriers between new varieties. This work is done by the plants 

 themselves. The varieties, at any rate all the large number that 

 have survived, have kept themselves apart. Through this inter- 

 sterility the bees have been gardeners who had each variety and 

 each species in an isolated garden, and for whom each new variety 

 as it arose proceeded to isolate itself without any trouble on their 

 part. They with their colour-sense and the plants with their 

 preference for pollen from one of their own species, or even for 

 pollen from one of their own variety have, working together, given 

 us all the colours, shapes, and scents of flowers. 



F. W. Headley. 

 Haileybuhy College. 



