No. 435 ] ANIITHETIC VERSUS HOMOLOGOUS. 169 



forerunner of the root developed later, which puts the sporophyte 

 into direct communication with the earth, thus rendering it 

 independent of the gametophyte. With the estahlishment of a 

 true root-system, capable of unlimited development t<> keep pace 

 with the growth of the aerial portions of the sporophyte, there 

 began a new era in the history of the vegetable kingdom, which 

 has culminated in the myriad types of vascular plants which now 

 cover the earth. 



