142 



Outline of Genetics 



tion is clear. After the germination of the megaspore, 

 everything within the old megaspore wall is gametophyte 



Archegonium 



Egg 



Old Megaspore \ { ^^ \__ \- Fusion Nucleus 



Wall, Inclosing 



Female Gametophyte _ 



Old Megaspore 



Wall, Inclosing 



Female Gametophyte 



Gymnosperm 



Angiosperm 



OVULE 



Gymnosperm 



Embrya 

 Megaspore Wall 



Endosperm 



SEED 



Angiosperm 



Embryo 

 Megaspore Wall 



Endosperm 



Fig. 23. — Diagram contrasting young ovules and mature seeds of 

 gymnosperms and angiosperms. 



tissue; fertilization affects the egg only, resulting in a 

 sporophyte embryo. In the seed, therefore, the embryo 

 is imbedded in nutritive tissue which is evidently the 



