thick midrib,
which, in the figure, is shown cut through just above the base. Not only
is the ordinary semilunar band of vascular tissue to be here seen, but a
similar broken line of vessels exists on the upper side of the
leaf-stalk; thus the whole structure resembles that of a stem or a
branch as much as that of a true leaf.

[Illustration: FIG. 210.--Section through base of midrib of cabbage
leaf, showing supplementary laminae, &c.]

The development of secondary leaves from the surfaces of primary ones
(phyllomania, autophyllogeny) has already been alluded to at p. 355.

Some of the cases wherein a leaf seems to have a double lamina may be
alluded to here, though possibly they would more properly be referred to
fission. The appearance presented is as if four wings projected from the
midrib, so that a cross section would be nearly in the form of
[Symbol: )O( turned 90 degrees.]. In an orange leaf presenting this
appearance the lower surface of one lamina was, as usual, dull in
colour, while the upper surface of the subjacent lamina was likewise
dull; hence the impression might arise that this was an instance of the
adhesion of two leaves back to back, but the petioles were not twisted,
as they must have been had two leaves thus been united, and neither in
the petiole nor in the midrib was there the slightest indication of
fusion, the vascular bundles being arranged in a circular manner, not in
a horseshoe-like arrangement, as would have been the case had adhesion
taken place.[518] (See p. 33.)

Such leaves as those of the hedgehog holly, _Ilex Aquifolium_, var.
_feroae_, and, to a less extent, bullate leaves, may also be mentioned
here as illustrations of hypertrophy or enation.

[Illustration: FIG. 211.--_Nephrodium molle_. Ordinary frond and forked
and crested varieties of the same, the crest arising from the inordinate
development of the margins of the pinnules.]

When the increased development occurs at the margin of the leaves,
especially, the result is a wavy or crisped appearance, "folia undulata,
_vel_ crispa."[519] These conditions occur normally in such leaves as
those of _Rumex crispus_, _Malva crispa_, &c., and are developed to an
extreme degree in garden varieties of parsley, some kails, &c., as well
as in many ferns, but these are probably cases rather of fission than
enation as here understood.[520]

=Enation from the sepals.=--The basal lobes of the calyx in _Campanula
Medium_, under normal cir