332 Plant Life and Evolution 



plant are not parts of the sporophyte at all, 

 but belong to the insignificant sexual generation, 

 or gametophyte, included within the ovule, or devel- 

 oped from the pollen-spore during its germination. 

 The embryo develops, not into a gametophyte like 

 the plant which produces the egg, but into a sporo- 

 phyte, which produces non-sexually myriads of 

 spores, embryo-sacs or pollen-spores, which in turn 

 develop the gametophytes. A single fertilization, 

 therefore, results ultimately in an enormous number 

 of new gametophytes, although years may elapse 

 before the sporophyte becomes large enough to 

 flower and produce its crop of spores. Now to as- 

 sume that there is a special germ-plasm, which is 

 passed on from the tiny gametophyte to the non- 

 sexual and long-lived sporophyte, and finally segre- 

 gated in the spores, and again passed along to the 

 next generation of gametophytes is, to say the least, 

 improbable. 



Subordination of Sex in the Higher Plants 

 The relative unimportance of sex in plants is shown 

 by the predominance of the asexual condition in all 

 of the higher plants. It is in the more primitive 

 aquatic forms, like the algae or the amphibious 

 archegoniates, that sexuality is best developed, and 

 it is evident that this is directly associated with 

 their aquatic life, as in these plants the sperms are 

 motile and require water for their transport. In 

 the more highly developed land plants sexuality be- 

 comes more and more subordinated, and not in- 



