158 Plant Life and Evolution 



precedes the formation of the endosperm is not to 

 be regarded as a real fertilization. 



The Fruit. The effect of fertilization extends 

 beyond the ovule itself, and the carpels within which 

 the developing seed are enclosed are also stimulated 

 into growth as the result of pollination, and at ma- 

 turity enclose the ripened seed within a " fruit." 

 It is probable that the development of the fruit, 

 evidently a highly important means for protecting 

 the seed, has been one of the factors in the success 

 of the angiosperms in their struggle for existence. 

 The variety of fruits is almost as great as that 

 of flowers, and it is quite as evident in many cases 

 that the modifications of the fruit are associated 

 with animals, which play an important part in the 

 distribution of the seeds of the angiosperms. Some 

 of the modifications of fruits which are pretty cer- 

 tainly concerned with their distribution through ani- 

 mal agencies, are the development of edible pulp, 

 either from the carpels themselves or from neigh- 

 boring tissue, and the development of grappling or- 

 gans, hooks, or spines, or occasionally an adhesive 

 pulp, as in the fruit of the mistletoe. Many fruits 

 and seeds are especially adapted for distribution by 

 the wind, as for example the wind-borne fruits and 

 seeds of the willow, catalpa, dandelion, and ma- 

 ple. There is no doubt that these many successful 

 methods of fruit distribution were also important 

 factors in establishing the ascendency of the angio- 

 sperms. 



