102 NATURE STUDIES. 



A flower is at bottom merely a device for producing 

 seed. But in order that the seed may prove capable 

 of germinating, the ovules in its carpels must 

 necessarily be fertilised by pollen. JSTow, all the 

 earliest flowers consisted merely of stamens and car- 

 pels ; they had no petals at all. But, as Mr. Darwin 

 has shown, flowers which are fertilised by pollen from 

 a neighbouring plant produce more seed and healthier 

 seedlings than those which are fertilised by the 

 produce of their own stamens. Hence, any modifica- 

 tion which promoted such cross-fertilisation would 

 benefit the plants in which it occurred by giving them 

 an advantage over their rivals in the struggle for 

 existence. Now, there are two ways in which flowers 

 have thus acquired special adaptations for fertilising 

 one another. Some of them have developed hanging 

 stamens which shake out their pollen to the wind, and 

 such flowers are also provided with feathery collecting 

 surfaces to the carpels, so as to catch the stray grains 

 which may happen to be wafted to them from their 

 neighbours by the breeze. Plants of this type never 

 possess bright- coloured petals. A second class, on 

 the other hand, have learned to utilise the winged 

 insects which visit their blossoms in search of food- 

 These welcome little pilferers, in passing from head to 

 head, carry the pollen of one plant to the carpels of 

 another, and so assist the flower in effecting the desired 

 cross-fertilisation. This class, to which the buttercup 

 belongs, has usually developed various inducements of 

 food, scent, and colour, in order to attract the fertilising- 



