124 BOTANY 



ovule is transformed into the seed, the stimulus to 

 growth, which the act of fertilisation of the ovum ad- 

 ministered to the latter, affects also the parts in its 

 neighbourhood. We have seen the embryo sac enlarg- 

 ing and the integuments of the ovule developing into the 

 testa of the seed. The ovary, too, resumes development 

 and increases in size, often enormously, by a large pro- 

 duction of succulent cells. When its full dimensions 

 have been attained the nature of the cells and their 

 contents changes. In some cases they become woody, 

 hard, and dry; in others succulent and charged with 

 sugar and various flavouring matters. These latter 

 changes make up the process known as ripening. The 

 enlarged dry or succulent wall is now known as a peri- 

 carp, and with the seeds which it contains it constitutes 

 the fruit. The latter is the modified wall of the ovary, 

 much changed and developed by the processes of growth 

 which have followed fertilisation. The fruit is thus a 

 mechanism which is concerned chiefly with the problem 

 of the dispersal of the seeds ; it plays also an important 

 protective function during the maturing of the seeds, 

 though this is not its main purpose. 



In some plants the renewed development does not 

 stop at the ovary or the carpels. Other parts of the 

 flower are involved, generally the axis or receptacle, as 

 in the apple, strawberry, etc. In some cases the leaves 

 of the perianth also become succulent. 



In yet other cases the development affects simul- 

 taneously all the flowers of a closely arranged inflores- 

 cence. All become succulent and fused together to 

 form a single fruit, as in the pine-apple and the fig. 



There are thus many intricacies of development and 

 the construction of the fruit is often complicated. Its 

 purpose is to distribute the seeds over a wide area. 



The lines of the development of the fruit are in 

 almost all cases the same at the outset. The parts 



