he perforation
of the pistillum, and the exposure of that point of the ovulum where the
embryo is formed to the direct action of the pollen; the second from the
too great simplicity of structure of the supposed ovulum, which, I have
shown, accords better with that of the nucleus as existing in ordinary
cases.

To the opinions of MM. Richard and Mirbel, the first objection does not
apply, but the second acquires such additional weight, as to render those
opinions much less probable, it seems to me, than that which I have
endeavoured to support.

In supposing the correctness of this opinion to be admitted, a question
connected with it, and of some importance, would still remain, namely,
whether in Cycadeae and Coniferae the ovula are produced on an ovarium of
reduced functions and altered appearance, or on a rachis or receptacle.
In other words, in employing the language of an hypothesis, which, with
some alterations, I have elsewhere attempted to explain and defend,
respecting the formation of the sexual organs in Phaenogamous plants,*
whether the ovula in these two families originate in a modified leaf, or
proceed directly from the stem.

(*Footnote. Linnean Society Transactions volume 13 page 211.)

Were I to adopt the former supposition, or that best agreeing with the
hypothesis in question, I should certainly apply it, in the first place,
to Cycas, in which the female spadix bears so striking a resemblance to a
partially altered frond or leaf, producing marginal ovula in one part,
and in another being divided into segments, in some cases nearly
resembling those of the ordinary frond.

But the analogy of the female spadix of Cycas to that of Zamia is
sufficiently obvious; and from the spadix of Zamia to the fruit-bearing
squama of Coniferae, strictly so called, namely, of Agathis or Dammara,
Cunninghamia, Pinus, and even Araucaria, the transition is not difficult.
This view is applicable, though less manifestly, also to Cupressinae; and
might even be extended to Podocarpus and Dacrydium. But the structure of
these two genera admits likewise of another explanation, to which I have
already adverted.

If, however, the ovula in Cycadeae and Coniferae be really produced on
the surface of an ovarium, it might, perhaps, though not necessarily, be
expected that their male flowers should differ from those of all other
phaenogamous plants, and in this difference exhibit some analogy to the
structure of the female flower.