s. It cannot, of course, be maintained
that the Bennettiteae, or any other Mesozoic Cycadophyta at present
known, were on the direct line of descent of the Angiosperms, for there
are some important points of difference, as, for example, in the great
complexity of the stamens, and in the fact that the ovary-wall
or pericarp was not formed by the carpels themselves, but by the
accompanying sterile scale-leaves. Botanists, since the discovery of the
bisexual flowers of the Bennettiteae, have expressed different views as
to the nearness of their relation to the higher Flowering Plants, but
the points of agreement are so many that it is difficult to resist the
conviction that a real relation exists, and that the ancestry of the
Angiosperms, so long shrouded in complete obscurity, is to be sought
among the great plexus of Cycad-like plants which dominated the flora
of the world in Mesozoic times. (On this subject see, in addition
to Wieland's great work above cited, F.W. Oliver, "Pteridosperms
and Angiosperms", "New Phytologist", Vol. V. 1906; D.H. Scott,
"The Flowering Plants of the Mesozoic Age in the Light of Recent
Discoveries", "Journal R. Microscop. Soc." 1907, and especially E.A.N.
Arber and J. Parkin, "On the Origin of Angiosperms", "Journal Linn.
Soc." (Bot.) Vol. XXXVIII. page 29, 1907.)

The great complexity of the Bennettitean flower, the earliest known
fructification to which the word "flower" can be applied without forcing
the sense, renders it probable, as Wieland and others have pointed
out, that the evolution of the flower in Angiosperms has consisted
essentially in a process of reduction, and that the simplest forms
of flower are not to be regarded as the most primitive. The older
morphologists generally took the view that such simple flowers were to
be explained as reductions from a more perfect type, and this opinion,
though abandoned by many later writers, appears likely to be true when
we consider the elaboration of floral structure attained among the
Mesozoic Cycadophyta, which preceded the Angiosperms in evolution.

If, as now seems probable, the Angiosperms were derived from ancestors
allied to the Cycads, it would naturally follow that the Dicotyledons
were first evolved, for their structure has most in common with that of
the Cycadophyta. We should then have to regard the Monocotyledons as
a side-line, diverging probably at a very early stage from the main
dicotyledonous stock, a view which many bo