40 THE FERTILISATION OF FLOWERS. [CHAP. 



all this trouble ? What benefit do they derive from 

 the transaction ? These are questions which will 

 probably have occurred ere this to the reader's mind. 

 They are easily answered by the facts so, too, are 

 many others in connection with flowers that used to 

 puzzle people to explain satisfactorily. Why are 

 flowers provided with honey and sweet perfumes? 

 Why are flowers highly coloured ? Why do flowers 

 "go to sleep" i.e., close their petals at night, and 

 in rainy weather ? 



These and many other questions are answered 

 by modern science satisfactorily. The insects are 

 attracted from a distance by the perfume of thq 

 flower ; they are shown the exact spot by the colour 

 of the corolla ; and they evidently are aware, from in- 

 herited instinct, that sweet odours and bright hues are 

 the outward signs of a store of honey. The insects 

 find their reward in the honey; the honey, then, is 

 only a bait to induce the insect to visit the flower, 

 and detach and carry the pollen. Flowers which are 

 fertilised by bees or butterflies, which fly by day, 

 close their petals at night, for it would not be to their 

 advantage to have their honey stolen by night-flying 

 moths, who cannot fertilise them. On the contrary, 

 night-flowering plants keep the petals closed during 

 the day, because they are fertilised by moths; and 

 to render them conspicuous they are light in colour. 

 Thus, the White Campion, which flowers at night, is 

 of a silver-white hue, and the light-yellow Evening 

 Primrose has the additional assistance of a very 

 strong sweet perfume. Flowers, too, close in rainy 

 weather to protect their honey. Many flowers which 



