that
in all cases it is the under surface of the leaf, or its modification,
from which new growths originate, and as nature has closed indusia, how
could the under surface be interior if this rule were not regularly
adhered to?

That the indusium is a _special_ organ, i.e. not an eruption of the
cuticle, I am sure; hence it is essential to examine extensively both
indusiate and other forms, the precise extension of their veins, etc. at
an early period to ascertain if their most diversified situations cannot
be reduced to some one type.

_Query_. Is the gyrate vernation of any ferns comparable to the form of
certain shells, to which (at least Mollusca) ferns are supposed to be
analogous.

_Memo_. To ascertain the most peculiar, and most universal points of
Mollusca and Pseudo cotyledonea, it is in this way that we may hope to
extend our views. Some there are indeed who, while the whole course of
their studies has been to neglect structure, deny the applicability of
presumptive evidence in favour of doctrines, the subjects of which are
barely susceptible of direct proof. Thus Greville and Arnott, angrily
ask, what do persons mean by saying that mosses have pistilla, etc.? they
protest against such community of application in the use of terms. Many
more deny sexuality because it has not been proved. Considering the
invisible nature of the fluid of the anthers of mosses, etc. how do they
expect that we are to demonstrate its application to the pistil, and the
subsequent steps? As well might they doubt the necessity of the
application of the boyau to an ovule, (or the existence of the boyau
itself,) because the derivation of the embryo cannot be proved.

One word more; in all cases the appearance of the reproductive body after
impregnation, is of late date; that date becomes later as we descend the
scale. The embryonary sac of Phaenogams does not always exist at the
time of application of the boyau, and the appearance of the embryo is
always posterior to this.

Again, ferns are superior to mosses in this, that in many cases the male
influence is exerted directly on the parts that become the thecae, which
is not the case in mosses.

_18th_.--Continued examining ferns, and to-day completes my knowledge of
the ramenta of three different genera.

In the first which is Cryptogamma, the resemblance of the young ramenta
to the anthers of Jungermannia is evident enough, they are capital, and
the head is at one peri