118 PROF. BOWER : 
This is neither the time, nor the place to describe in detail the results 
whieh have followed from this more searching application of the Natural 
Method of Classification to the Filicales. It must suffice to say that in 
certain features they coincide with the results of the older Systematists, 
which were based largely on external features. This is a high testimony to 
the acuteness of their perception of affinity. But it applies rather to the 
genera and species than to the larger groups. We have seen how assumed 
affinities or mere circumstance appear to have determined the arrange- 
ment of these in the ‘Synopsis Filicum.’ There is little evidence of any 
better method in the arrangement in Engler’s ‘ Natiirlichen Pflanzen- 
familien’? The Hymenophyllacese are there placed first, and then in 
succession the Cyatheacee,  Polypodiaces, Parkeriacew, Matoniaces, 
Gleieheniaces, Schizæaceæ, and Osmundacee ; while the Hydropterides 
are spliced in between these and the Marattiaceæ and Ophioglossacex. It 
is difficult at first sight to trace any method in such a disposition. It may, 
however, be seen to coincide in the leading features with the views of Prantl. 
For he regarded the Hymenophyllacee as the source of the Lepto- 
sporangiates and the Schizæaceæ as the source of the Eusporangiates, 
these two main phyla being distinct. The arrangement is better in Christ's 
* Farnkrüuter'; for the Eusporangiates, though placed last, are at least 
in near relation to other Simplices. But it would be difficult to justify 
phyletically the juxtaposition of the Hymenophyllacez, still placed first 
of all, with the Acrosticheze, which immediately follow them. The plain 
fact is, that up to the end of the 19th Century there was little attempt 
at a definite method in the disposition of the main groups of Ferns in 
the Systematic Works. The larger groups were still treated as though 
they represented types isolated from one another in their Descent. It is 
true that Prantl (Arb. Kónigl. Bot. Garten zu Breslau, 1892) represented 
by a graphic figure his conception of the phyletic relations of the main 
groups. But that figure shows that he believed his Osmundales (which 
included the Eusporangiates, together with the Schizwacex, Gleicheniacez, 
and Osmundacee) to be phyletically distinct from his Pteridales (which 
ineluded all other Leptosporangiates). The one he traces from the 
Schizæaceæ ; the other from the Hymenophyllaces, which his figure 
suggests as having originated from some common but unknown ancestor. 
This view is an improvement on the haphazard methods that preceded it. 
But it breaks the continuity of those lines of. descent which are now rapidly 
assuming clearer definition. 
Two channels of recent investigation have materially helped towards that 
clearer presentment : viz., the pursuit of vascular anatomy in Ferns, living 
and fossil ; and the study of those types which had suftered vicissitudes of 
classification, as shown by the richness of their synonymy. To the former 
the main contributions have been those of Russow, Poirault, the Bertrands 
father and son, Gordon, Boodle, Tansley, Kidston, Jeffrey, Gwynne- 
