220 THE RING OF NATURE 



key to a particular floral lock. You will never 

 see a hive-bee attempt to probe a primrose or 

 the tubes of the crimson clover. 



The step from green leaves to coloured for 

 advertising purposes was easy enough. The milk- 

 wort of our own day has a few leaves coloured in 

 addition to its regular petals, and these extra 

 leaves do not fall off when the purpose of the 

 flower is ended, but turn green and take up the 

 chemical functions of ordinary leaves. That 

 there is no great fundamental difference between 

 petals and stamens is shown by the water-lily, 

 which has petals with anthers on them and stamens 

 without anthers as though they had half a mind to 

 be petals. 



When a descendant of some early spore-bearing 

 plant had devoted a whorl of leaves to the 

 stigmatic function, the next whorl to the provision 

 of pollen and glands at the base for the secretion 

 of honey, the next whorl to advertising purposes 

 as petals, and a fourth as special wraps for the 

 tender parts of the blossom (sepals), it had marked 

 a very great advance upon the spore system of 

 its ancestor. Its attendant insects, too, were 

 far different from the promiscuous rabble whose 

 robberies had started the whole movement. But 

 both flower and insect had still far to go. 

 Further adaptations to the visits of favoured 

 insects have given us and are giving us such things 

 as the petal of special shape to shelter the stamens 

 of the sage, stamens with a wonderful trap arrange- 



