s. I am not entirely satisfied, however, with the observations I
have hitherto been able to make on a subject naturally difficult, and to
which I have not till lately attended with my present view.

The facts most likely to be produced as arguments against this view of
the structure of Coniferae, are the unequal and apparently secreting
surface of the apex of the supposed nucleus in most cases; its occasional
projection beyond the orifice of the outer coat; its cohesion with that
coat by a considerable portion of its surface, and the not unfrequent
division of the orifice of the coat. Yet most of these peculiarities of
structure might perhaps be adduced in support of the opinion advanced,
being apparent adaptations to the supposed economy.

There is one fact that will hardly be brought forward as an objection,
and which yet seems to me to present a difficulty, to this opinion;
namely, the greater simplicity in Cycadeae, and in the principal part of
Coniferae, of the supposed ovulum which consists of a nucleus and one
coat only, compared with the organ as generally existing when enclosed in
an ovarium. The want of uniformity in this respect may even be stated as
another difficulty, for in some genera of Coniferae the ovulum appears to
be complete.

In Ephedra, indeed, where the nucleus is provided with two envelopes, the
outer may, perhaps, be supposed rather analogous to the calyx, or
involucrum of the male flower, than as belonging to the ovulum; but in
Gnetum, where three envelopes exist, two of these may, with great
probability, be regarded as coats of the nucleus; while in Podocarpus and
Dacrydium, the outer cupula, as I formerly termed it,* may also, perhaps,
be viewed as the testa of the ovulum. To this view, as far as relates to
Dacrydium, the longitudinal fissure of the outer coat in the early stage,
and its state in the ripe fruit, in which it forms only a partial
covering, may be objected.** But these objections are, in a great
measure, removed by the analogous structure already described in Banksia
and Dryandra.

(*Footnote. Flinders Voyage volume 2 page 573.)

(**Footnote. Id. loc. cit.)

The plurality of embryos sometimes occurring in Coniferae, and which, in
Cycadeae, seems even to be the natural structure, may also, perhaps, be
supposed to form an objection to the present opinion, though to me it
appears rather an argument in its favour.

Upon the whole, the objections to which the view here taken