the more primitive type in the Ferns f 1 1 1 
a higher position in the developmental tree : this view 
I shared when writing, two years ago, the paper above quoted : 
I there definitely stated, however, that the converse view was 
capable of defence (p. 374) ; in fact, that the simpler Ferns 
might be regarded as forms which had degenerated, and owe 
their more delicate structure to adaptation to life in moist 
shade : but this view I did not then accept. Subsequently 
the question has been taken up by D. H. Campbell 1 , who has 
argued in favour of the Eusporangiate forms as being primitive 
rather than derivative : yet, though he has brought forward 
various points of interest and importance, the whole matter 
has not been by any means exhausted, and I therefore propose 
to look into the evidence which may be adduced in support of 
the two views, and to consider first what basis of evidence 
there actually is in favour of the view now currently held. 
Seeing that the broadest lines of progress of evolution have 
commonly led from the smaller and simpler to the larger and 
more complex, there has been a general disposition to assume 
that the simpler terms of any series are the more primitive. 
This assumption has doubtless affected the views of botanists 
with regard to the Ferns, and has led to the established 
opinion that the Hymenophyllaceae, being structurally the 
simplest, approach the primitive Filicineous type more nearly 
than other living forms. But a simplification of structure has 
been recognised in so many cases as following on exposure to 
certain conditions of life, that the idea of degeneration has be- 
come a familiar one. We are therefore no longer justified in 
making the above assumption unless it be supported by a 
knowledge of the environment past and present, as well as by 
comparative evidence. For such evidence recourse must be 
had in the present case to lower rather than to higher forms, 
and the comparison has been commonly drawn between the 
Filmy Ferns and the Mosses: notwithstanding the wide differ- 
ences between them, it has been generally held that of all 
Vascular plants the Hymenophyllaceae approach most nearly 
to the Bryophyta. 
1 Botanical Gazette, Jan. 1890. 
