FRUITS. 95 



obtain a general conception of the structure and cycle of 

 development of flowering plants, but if we were to take a 

 single seed, and watch its germination and every detail of 

 its subsequent life and growth, we should find its develop- 

 mental history a connected synopsis of what we have 

 learned from so many sources. This may be stated briefly 

 as follows: In the spermaphytes, or higher plants, the 

 embryo arises from a single cell, the ob'sphere, contained 

 in the embryo-sac. The embryo has all the essential vege- 

 tative parts of the mature plant, and in germination these 

 are unfolded, finally developing into root, stem, and leaf. 

 Certain buds of the plant in this later stage of its develop- 

 ment become ordinary branches, while others undergo ex- 

 traordinary modifications and become reproductive branches 

 or flowers. In due course of time the oosphere is formed 

 in the embryo-sac of the various ovules, and after fertiliza- 

 tion the same history is repeated in a subsequent genera- 

 tion. Later on in our work we shall see that plants lower 

 in the scale of life exhibit similar, though not identical, 

 phases of developmental history. Before proceeding to 

 these, however, we have first to study certain relationships 

 of the higher plants among themselves. 



