ionally met with, as instances of the
cohesion of the margins at the base and apex of the leaf, which thus
appears perforated. This appearance, however, is probably due to some
other cause. When the leaves are verticillate and numerous, and they
become coherent by their margins, they form a foliaceous tube around the
stem. When there are but two opposite leaves, and these become united by
their margins, we have a state of things precisely resembling that to
which the term connate is applied.

Fusion of the edges of the cotyledons also occasionally takes place, as
in _Ebenus cretica_.[25] It has also been observed in _Tithonia_, and is
of constant occurrence in the seed leaves of some _Mesembryanthema_.
This condition must be carefully distinguished from the very similar
appearance produced by quite a different cause, viz., the splitting of
one cotyledon into two, which gives rise to the appearance as if two
were partially united together.

Some of the ascidia or pitcher-like formations are due to the cohesion
of the margins of two leaves, as in a specimen of _Crassula
arborescens_, observed by C. Morren.

[Illustration: FIG. 10.--Two-leaved pitcher of _Crassula arborescens_,
after C. Morren.]

The stipules may also be fused together in different ways; their edges
sometimes cohere between the leaf and the stem, and thus form a solitary
intra-axillary stipule. At other times they become united in such a
manner as to produce a single notched stipule opposite to the leaf.
Again, in other cases, they are so united on each side of the stem, that
in place of four there seem only to exist two, common to the two leaves
as in the Hop.

To the Rev. M. J. Berkeley I am indebted for specimens of a curious
pitcher-like formation in the garden Pea. The structure in question
consisted of a stalked foliaceous cup proceeding from the inflorescence.
On examination of the ordinary inflorescence, there will be seen at the
base of the upper of two flowers a small rudimentary bract, having a
swollen circular or ring-like base, from which proceeds a small
awl-shaped process, representing the midrib of an abortive leaf. In some
of Mr. Berkeley's specimens, the stipules were developed as leafy
appendages at the base of the leaf-stalk or midrib, the latter retaining
its shortened form, while, in others, the two stipules had become
connate into a cup, and all trace of the midrib was lost. The cup in
question would thus seem to have been form