138 Flowers and their Pedigrees. 



descendants ; and the existing petalless reeds or 

 cuckoo-pints, as well as the apparently petalless 

 wheats and grasses, are special adaptive forms of the 

 newer petal-bearing rushes and lilies. 



The origin of the coloured petals, we know, is 

 almost certainly due to the selective action of prima.'val 

 insects. The soft pollen, and perhaps too the slight 

 natural exudations around the early flowers, afforded 

 food to the ancestral creatures not then fully devel- 

 oped into anything that we could distinctively call a 

 bee or a butterfly. But as the insects flew about from, 

 one head to another in search of such food, they 

 carried small quantities of pollen with them from 

 flower to flower. This pollen, brushed from their 

 bodies on to the sensitive surface of the ovaries, 

 fertilised the embryo seeds, and so gave the fortunate 

 plants which happened to attract the insects all the 

 benefits of a salutary cross. Accordingly, the more 

 the flowers succeeded in attracting the eyes of their 

 winged guests, the better were they likely to succeed 

 in the struggle for existence. In some cases, the 

 outer row of stamens appears to have become flattened 

 and petal-like, as still often happens with plants in 

 the rich soil of our gardens ; and in these flatter 

 stamens the oxidised juices assumed perhaps a 

 livelier yellow than even the central stamens them- 



