REPRODUCTION 



107 



scale, protection is either afforded by the parent, 

 or the offspring itself has special protective adapta- 

 tions. Further, the parent lays aside reserve stores 

 in association with the embryo to start it in life. 



One striking difference makes itself evident in the 

 early stages of 

 existence of 

 higher plants 

 and of higher 

 animals respec- 

 tively. The 

 embryo animal 

 is nourished by 

 its parent and 

 develops con- 

 tinuously from 

 the moment of 

 fertilisation of 

 the ovum until 

 the embryo be- 

 comes able to 

 shift for itself, 

 but in the case 

 of the higher 

 plant the con- 

 ditions are 

 somewhat dif- F IG . 53. Winged fruits of Maple, 



ferent. The 



oosperm gradually develops into an embryo up^to 

 a certain stage and has, at the same time, reserve 

 food stored in it or round it. Then ensues a 

 period of rest, and in this condition it, along with 

 its food supply and protective structures, is known 

 as a seed. This resting stage, or seed-period, may 

 last for several months or even years, after which 



