THE QUEST OF PHYLETIC LINES 99 



the evolutionary history is most imperfect in its earliest chapters. 

 Nevertheless the question of origin by descent, and of the phyletic 

 relationships of these isolated and at the same time primitive 

 forms, has fastened itself upon the minds of our contemporaries 

 with a singular insistence. Perhaps the very difficulties which 

 such problems present are a source of their special attraction. 

 The result has been voluminous writing, in which argument out- 

 weighs fact, and criticism is often conducted without any clear 

 conception of what the canons of criticism should be. 



The Archegoniate forms have been the central field of phyletic 

 discussion just as the Low Countries were the fighting ground in 

 European wars. I do not propose here to allude in detail to 

 any of those various and divergent views relating to them and to 

 their place in descent, which have found partial or it may be gen- 

 eral acceptance in recent times, but to turn to opinions which 

 have been discarded. It will be possible to illustrate the diffi- 

 culties and fallacies which attend such discussions through the 

 medium of opinions which at their time claimed wide attention, or 

 even general adherence, but are now superseded. Useful lessons 

 may thus be learned, which will find their Application in criticism 

 of phyletic study as it now stands. 



Those whose botanical experience dates back to the seventies 

 of the last century will remember the position as almost axio- 

 matic, that the Leptosporangiate Ferns were the most primitive 

 Vascular Plants, and that all the rest were to be referred to that 

 source. Treatises still exist in print explaining the steps of such 

 derivation, and suggesting on a basis of comparison how the Eu- 

 sporangiate state originated from the Leptosporangiate, and how 

 by condensation of the fern-like shoot even the Psilotaceae and 

 Lycopods might be arrived at. If we analyse the steps leading to 

 such conclusions in the light of later experience it is possible to 

 find the flaws in the argument ; but in doing so there is no need to 

 sacrifice respect for their authors, who were often the leading 

 thinkers of their time. The prime error in the present instance 

 was a very natural assumption that those propagative organs 

 which are simplest in structure were the earliest in descent. The 

 delicate sporangium of a Scolopendrium or of a Davallia, with its 



