TRANSACTIONS OF SECTION K. 1001 
fruit of the Bryophyta. The plant of the Pteridophyta is sometimes small and 
pels, but the smallest and simplest seem just as unlike a bryophytic sporogonium 
as the largest and most complex. On the side of the moss group, Anthoceros has 
been often cited as a form showing a certain approach towards the Pteridophytes, 
and Professor Campbell in particular has developed this idea with remarkable in- 
genuity. An unprejudiced comparison, however, seems to me to show nothing more 
here than a very remote parallelism, not suggestive of affinity. ‘ 
There is no reason to believe that the Bryophyta, as we know them, were the 
precursors of the vascular Oryptogams at all. There is a remarkable paucity of 
evidence for the geological antiquity of Bryophyta, though mary of the mosses at 
any rate would seem likely to have been preserved if they existed. Brongniart 
said, in 1849, ‘ The rarity of fossil mosses, and their complete absence up to now 
in the ancient strata, are among the most singular facts in geological botany ;’* 
and since that time it is wonderful how little has been added. Things seem to 
point to both Pteridophyta and Bryophyta having had their origin far back 
among some unknown tribes of the Alge. If we accept the homologous theory 
of alternation, we may fairly suppose that the sporophyte of the earliest Pterido- 
phyta always possessed vegetative organs of some kind. The resemblance between 
the young sporophyte and the prothallus in some lycopods indicates that at some 
remote period the two generations may not have been very dissimilar. At least 
some such idea gives more satisfaction to my mind than the attempt to conceive 
of a fern-plant as derived from a sterilised group of potential spores. 
The Bryophyta may have had from the first a more reduced sporophyte, the 
first neutral generation having, in their ancestors, become more exclusively adapted 
to spore-producing functions. I must not omit to mention the idea that the 
Bryophyta, or at any rate the true mosses, are degenerate descendants of higher 
forms. The presence of typical stomata on the capsule in some cases, and of 
somewhat reduced stomata in others, has been urged in support of this view. It 
is possible ; but if so, from what have these plants been reduced ? 
Few people, perhaps, fully realise how absolutely insoluble such a problem as 
we have been discussing really is. I say nothing as to the mosses, which may 
have arisen relatively late in geological history. ‘he Pteridophyta, at any rate, 
are known to be of inconceivable antiquity. Not only did they exist in greater 
development than at present in the far-off Devonian period, but at that time they 
were already accompanied by highly organised gymnospermous flowering-plants. 
Probably we are all agreed that Gymnosperms arose somehow from the vascular 
‘Cryptogams. Hence, in the Devonian epoch, there had already been time not only 
for the Pteridophyta themselves to attain their full development, but for certain 
e#mong them to become modified into complex Phanerogams. It would not be a 
rash assumption that the origin of the Pteridophyta took place as long before the 
period represented by the plant-bearing Devonian strata as that period is before 
our own day. Can we hope that a mystery buried so far back in the dumb past 
will be revealed P 
It will be understood that I do not wish to assume the réle of partisan for the 
homologous theory of alternation. Possibly the whole question lies beyond human 
ken, and partisanship would be ridiculous. But I do wish to raise a protest 
against anything like a dogmatic statement that alternation of generations must 
have been the result of the interpolation of a new stage in the life-history. Let 
us, in the presence of the greatest mystery in the morphology of plants, at least 
keep an open mind, and not tie ourselves down to assumptions, though we may 
use them as working hypotheses. 
HistoLocicaL CHARACTERS OF THE TWO GENERATIONS. 
There is one histological question upon which I must briefly touch, because it 
bears directly on the subject which we have been considering. I shall say very 
little, however, in view of the discussion next, Tuesday. 
' Tableau des Genres,de Végétaux Fossiles, ps 13. 
1896. 37 
