86 THE STORY OF THE PLANTS. 



as the pistil, is the female individual ; it produces 

 ovules, or young seeds, which, however, cannot 

 grow and swell without the quickening aid of pol- 

 len. The next row in the flower, known as the 

 stamens, contains the male individuals; they pro- 

 duce pollen, w^hich lights on the sensitive surface 

 of the pistil, sends out tubes of very active living 

 matter, and quickens or impregnates the ovules 

 in the pistil. Besides these necessary organs flow- 

 ers have often two other sets of parts. The co- 

 rolla, which is made up of petals, united or dis- 

 tinct, is usually brightly coloured, and acts as an 

 advertisement or allurement to the insects; it oc- 

 curs chiefly in insect-fertilised flowers, and gener- 

 ally implies the presence of honey. The calyx or 

 outer cup, which is made up of sepals, distinct or 

 united, acts mainly as a protective covering. 

 Plants can fertilise themselves if necessary, but 

 in all the highest and most successful plants some 

 form or other of cross-fertilisation has become 

 almost universal. Self-fertilisation goes down the 

 hill ; cross-fertilisation is the road to success and 

 vigour. 



CHAPTER VII. 



VARIOUS MARRIAGE CUSTOMS. 



The simplest and earliest flowering plants 

 had probably only three sets of organs — leaves, 

 stamens, and pistils — w^orkers, males, and females. 

 Their flowers consisted at best of the necessary 

 organs, enclosed, perhaps, in a few protective 

 sheathing leaves, rather smaller than the rest, 

 the forerunners of a calyx. How, then, did mod- 



