236 



spermatogenesis, and conjugation. Any connection with spore-forma- 

 tion and an antithetic alternation of generations, such as that found 

 in the Metaphyta, would at that time, and long afterwards, have 

 appeared to me to be utterly absurd and chimerical. The track from 

 the start almost to the finish has been a complex and puzzling one. 

 Often it has been dark and ill-defined , and the goal has kept itself 

 concealed until well-nigh the journey's end. 



When the "supposed law of Metazoan development" ^) was written, 

 the recognition of any very close similarity in the laws governing 

 animal- and plant -development seemed somewhat remote. All along 

 the desire has been to study the facts, to ignore none, and not to be 

 biassed by theoretical considerations. For a long time no decisive 

 facts were unearthed; but, ultimately, putting together various facts 

 concerning larvae and their fate, their morphology, and their trans- 

 formations in allied forms, observations on the first appearance of 

 sexual characters in the Vertebrate embryo, the attainment of the 

 adult form of body, the formation of the definitive nervous system 

 in the fish embryo, and comparing the appearance of these latter fac- 

 tors with the period of commencing degeneneration of the transient 

 nervous apparatus, it became evident that the initiation of degeneration 

 was in association with a number of phenomena which could be 

 nothing other than a metamorphosis. And it then began to dawn 

 upon one that the development of a lower Vertebrate was in reality 

 an alternation of generations in which the sexual form began to be 

 formed upon an asexual foundation at a very early period. It was 

 then recognised that the two could only co-exist as long as the sexual 

 generation was, so to speak, merely dormant upon the asexual one, 

 and that, as soon as the former began to manifest activities in its 

 development, these led without fail to the suppression of the latter. 

 Owing to complete want of homology between the parts of the two 

 generations, as proved by their different nervous systems, and as 

 further manifested by numerous types with larval development among 

 the Invertebrata, it became obvious that Metazoan development was 

 really bound up with an antithetic alternation of generations. This 

 was the standpoint reached when I became acquainted with Bower's 

 researches and results on Apospory in ferns -). Then many things 



1) J. Beaed, On a supposed Law of Metazoan Development. Anat. 

 Anz., 1892. 



2) F. 0. BowEE, On Apospory and allied Phenomena. Trans. Linn. 

 Soo. Ser. Bot., Vol. II, Pt. 14, 1887. 



