as to
dehiscence. We have a tendency to fuscous colouring, a tendency to the
aggregation of congealed matter about the septae, precisely the places
where it is to be expected. The same appearance of a canal of
communication, the same irregular _constriction_ of certain cells; in
this too the first change in the pinnae, or its component lobes, is the
definition of the margin. In this genus the under surface of the frond
is covered with these _hairy-form_ bodies (which have been figured over
and over again in Hooker and Greville's ferns): on the upper face, a few
exist, but incomparably less developed.

From the examination of this genus alone, I do not think the idea I have
been so diffuse upon, would have struck me.

To-morrow I examine Ceterach, assured that the scales of its under face
are reducible to the same type. In a matter of such interest and
importance as this, many will, and with reason, dislike so important an
assumption on such inconclusive evidence. But with our present means, it
appears to me probable that no evidence to demonstration can be looked
for, and for this reason, that the contents of these peculiar cells are
so subtile as to escape definition even while in their cells, (or under
the most favourable circumstance for a concentration of attention.) How
much more so will this be the case, when we attempt to examine the steps
of the application of the fecundatory matter, applied over a surface
without any prominent points, and probably opaque.

When direct evidence is not to be had, we are justified in using
presumptive evidence. As in human law, so in the laws of nature,
presumptive evidence to a practised eye carries with it conviction. We
have no direct evidence how the embryo is formed, yet no one doubts but
that it is brought about by the agency of the boyau, which is a cell
containing grumous molecular matter. However different a boyau may seem
to many, yet when viewed in conjunction with Cycadeae, the graduation to
the present case becomes natural, and even the resemblance may be
perfect, because in Cycas the grains of pollen get into the nucleus
bodily, although they would still seem to throw out short tails.

Wonderful is the simplicity of nature! The male organ in its essence,
consists of a single cell containing molecular matter.

The female in its essence consists of a single cell, likewise containing
similar matter. The influence of the male is exerted, and so another
ce