to. The
instance is that of the subdivision of the leaf-like organs of
_Sciadopitys verticillata_. In one instance the pseudo leaf divided, and
from the division proceeded a little axis, bearing at its summit a
verticil of pseudo leaves. This division and formation of new axes and
verticils affords ample confirmation of the opinion thrown out by
Professor Alexander Dickson, that the apparent leaves of this plant were
really branches: see 'Revue Horticole,' 1867, and 'Report. Bot.
Congress,' London, 1866, p. 124.

CHAPTER II.

MULTIPLICATION OF FOLIAR ORGANS.

The cases referrible to this head may be ranged under two sections
according as the increase is due to plurality of ordinarily single
organs, or to an increase in the number of verticils or whorls.

When, in place of a single leaf organ two or more are really or in
appearance present the occurrence may be due to one of several causes;
among them may be mentioned an actual formation of parts in unwonted
number, hypertrophy or enation, chorisis or fission, disjunction,
adhesion of one leaf to another or to the stem, as in some of the leaves
called "geminate," wherein the two leaves, though apparently in
juxtaposition, yet originate from different parts of the stem, but by
coalescence or lack of separation produce the impression as if they
sprang from the same node. In the adult state it is not always possible
to ascertain with certainty to which of these causes the increase in the
number of leaves is due, though a clue to the real state of things may
be gained from attention to the distribution of the veins, to the
arrangement or phyllotaxy of the leaves, the size and position of the
supernumerary organs, &c.

The term "phyllomania," as ordinarily used, is applied to an unwonted
development of leafy tissue, as in some begonias where the scales or
ramenta are replaced by small leaflets, or as in some cabbage leaves,
from the surface of which project, at right angles to the primary
plane, other secondary leafy plates; but these are, strictly speaking,
cases of hypertrophy (see Hypertrophy).

Those instances in which the actual number of leaves is increased, so
that in place of one there are more leaflets, may be included under the
term "pleiophylly," which may serve to designate both the appearance of
two or more leaves in the place usually occupied by a single one, and
also those normally compound leaves in which the number of leaflets is
greater than