64 PLANT LIFE. 



of the seed-plants that thay will be discussed in connection 

 with them. 



Seed-plants. 



Among the highest plants, those which produce seeds, the 

 differentiation of the body is essentially the same. The 

 alternation of sexual and non-sexual phases is still traceable, 

 though greatly obscured l)y the extreme reduction of the 

 gametophvte. This tendency to the reduction of the sexual 

 phase, which was rcmarl;ed in passing from the mossworts to 

 the fernworts, continues, until in the highest seed-plants the 

 gametophyte is wholly microscopic. Even by the aid of the 

 microscope, it is possible to identify only the sexual organs 

 which it produces, and one or more cells which are, perhaps, 

 the rudiments of its vegetative body. The sjiorophyte, con- 

 se(4uently, is the only phase of the seed-plant visible to the 

 unaided eye. The relation of the gametophyte to it will be 

 explained in Part III. 



The body of the S[)orophyte exhibits the same members, 

 viz., stem, root, and leaf, having the same general form, and 

 subject to the same modifications, as in the fernworts. To a 

 discussion of the ^■egetative members of the fernworts and 

 seed-plants we now turn. 



