PART II. 

 INTRODUCTION. 



WE proceed now to deal with the detailed statement of facts bearing on 

 the theoretical position expounded in the First Part of this work. The 

 arrangement to be adopted must not be understood as indicating any definite 

 opinion as to kinship of the several phyla described : it is often dictated 

 by convenience of exposition, as much as by the estimate of degrees of 

 affinity. Moreover, to any who entertain a belief in polyphyletic origins, 

 it will be clear that any simple serial sequence must be misleading. The 

 primary end here pursued is not to assign degrees of affinity to the 

 relatively isolated relics of a former World-Flora : such relations must 

 always remain highly problematical, so long as the data remain as incom- 

 plete as they at present are. The object is rather to frame some general 

 idea of the methods of advance of the sporophyte ; and to trace the effects 

 of those methods from its simpler beginnings to its final condition as an 

 independent plant, forming the essential feature of the Flora of the Land. 

 Such a study must depend largely on details. Those details will now be 

 put together in systematic sequence. 



It may be objected that the scheme of this book is a reversal of the 

 ordinary logical procedure of using the facts as a basis for the conclusions. 

 But in point of fact, it is not so : for in writing the preceding chapters 

 which have dealt with the general theory, all the data now to be 

 described were before the mind of the author, and formed the natural 

 foundation of his thoughts. It is for the convenience of readers that the 

 working hypothesis has been stated first, so as to convey the point of 

 view from which the facts may be examined and appraised. The detailed 

 statement will thus be more intelligible in its bearing on the question of 

 the origin of a Land-Flora, than would otherwise have been possible. 

 It will hardly be necessary to repeat again that the general [theory of the 

 foundation of a Land-Flora as a concomitant of antithetic alternation 

 has been stated only as a "working hypothesis^': it is now to be tested 

 by its applicability to the details which are to follow. The course adopted 



