350 NATURE STUDY AND AGRICULTURE 



a young sporophyte. At the same time the ovule (spor- 

 angium) produces a hard coat, and the whole structure is 

 called the seed. In a seed, therefore, we see that three 

 generations are represented: the ovule (sporangium) be- 

 longs to the old sporophyte, and is always represented by 

 at least the testa or hard outer coat of the seed. Within the 

 outer part of the old ovule lies imbedded the female gameto- 

 phyte, which resulted from the germination of the mega- 

 spore, grew as an internal parasite, bore the now fertilized 

 egg, and after fertilization constitutes that part of the seed 

 commonly known as endosperm. Finally, and innermost, 

 imbedded within the female gametophyte, lies the third 

 generation which is included in this wonderful organ, the 

 seed. This innermost of the three members of the seed is the 

 young sporophyte of the yet undeveloped generation, and it 

 is called the embryo. Thus we should see that it is im- 

 possible to know what a seed really is unless we approach 

 it from the lower groups and come to an understanding of 

 its evolution. 



