educible to a _marginal production_ of the reproductive
apparatus. I will bear this in mind, as certain forms of Pteris or its
affinities lead me to suspect that in these tribes the indusium may be a
long way from the margin, and yet be, quoad origin, marginal; this
section illustrates my meaning.

[Fern sections: m444.jpg]

The transition to this might reasonably be suspected. The philosophy of
ferns is most ill understood, the higher points connected with them have
been quite neglected, and botanists in this as in other departments of
the science have been contented to confer names on certain external
forms, without sufficient regard to structure.

To-day I commenced examining Adiantum, with the view of determining if
possible the nature of its reproductive organs, and the mode in which
they are impregnated, if they are impregnated at all.

As I had long been aware that the fructification of each frond is a thing
to be determined at a very early period, and that if not determined then,
it is never likely to be determined afterwards, my attention was directed
more strongly, if possible, than it would have been otherwise, to
examining the subject at the earliest possible stage of its development.

The first piece examined gave me the idea that I had trouve le noeud de
l'affaire; the second made me doubt this; the subsequent ones went far to
disprove it.

I was immediately struck with the resemblance of those organs, called
ramenta, to what are fairly assumed to be the male bodies, in certain
other families of the same grand division; and I at once came to the
conclusion, that the barren fronds, were barren, because almost destitute
of these ramenta; and that as these ramenta were confined to the base of
the stalk, that is, to the part below its first ramification, an obvious
necessity existed for the peculiar nature of the vernation.

Further examination of the thing, especially of the base of the stipes
and the adjoining part of the rhizoma, threw me back almost into my
original difficulties. I find that the rhizoma is entirely covered with
ramenta, which are brown, much detached at the base, and obviously
represent a low form of leaf, i.e. in appearance, perhaps partly in
function, but not in structure. Among these, mature ramenta at the
punctas of prolongation, which appear to be very irregular, are
concealed, others much smaller, and much narrower, (which bear as obvious
a resemblance, or even more so to