.
As evolution went on, one function was superadded on another, and
it appears impossible to resist the conclusion that the whole
differentiation of the seed was a process of adaptation, and
consequently governed by Natural Selection, just as much as the
specialisation of the rostellum in an Orchid, or of the pappus in a
Composite.

Did space allow, other examples might be added. We may venture to
maintain that the glimpses which the fossil record allows us into early
stages in the evolution of organs now of high systematic importance,
by no means justify the belief in any essential distinction between
morphological and adaptive characters.

Another point, closely connected with Darwin's theory, on which the
fossil history of plants has been supposed to have some bearing, is
the question of Mutation, as opposed to indefinite variation. Arber and
Parkin, in their interesting memoir on the Origin of Angiosperms,
have suggested calling in Mutation to explain the apparently sudden
transition from the cycadean to the angiospermous type of foliage, in
late Mesozoic times, though they express themselves with much caution,
and point out "a distinct danger that Mutation may become the last
resort of the phylogenetically destitute"!

The distinguished French palaeobotanists, Grand'Eury (C. Grand'Eury,
"Sur les mutations de quelques Plantes fossiles du Terrain houiller".
"Comptes Rendus", CXLII. page 25, 1906.) and Zeiller (R. Zeiller
"Les Vegetaux fossiles et leurs Enchainements", "Revue du Mois", III.
February, 1907.), are of opinion, to quote the words of the latter
writer, that the facts of fossil Botany are in agreement with the sudden
appearance of new forms, differing by marked characters from those that
have given them birth; he adds that these results give more amplitude
to this idea of Mutation, extending it to groups of a higher order,
and even revealing the existence of discontinuous series between the
successive terms of which we yet recognise bonds of filiation. (Loc.
cit. page 23.)

If Zeiller's opinion should be confirmed, it would no doubt be a serious
blow to the Darwinian theory. As Darwin said: "Under a scientific point
of view, and as leading to further investigation, but little advantage
is gained by believing that new forms are suddenly developed in an
inexplicable manner from old and widely different forms, over the old
belief in the creation of species from the dust of the earth." ("Origin
of Species