case in which one of the prickles on
the fruit of a cucumber had grown out into a tendril.

In _Cobaea scandens_ the foliar nature of the tendril is shown by the
occasional presence of a small leaflet on one of the branches of the
tendril, and a similar appearance may frequently be seen in
_Eccremocarpus scaber_. On the other hand, in the vine, the axial nature
of the tendril is revealed by the not infrequent presence of flowers or
berries on them, as also in _Modecca_ and some _Passifloraceae_.

Darwin, speaking of the tendrils of _Bignonia capreolata_, says it is a
highly remarkable fact that a leaf should be metamorphosed into a
branched organ, which turns from the light, and which can, by its
extremities, either crawl like a root into crevices, or seize hold of
minute projecting points, these extremities subsequently forming
cellular masses, which envelope by their growth the first fibres and
secrete an adhesive cement.

=Interrupted growth.=--This term is here used in the same sense as in
ordinary descriptive botany, as when an "interruptedly pinnate" leaf is
spoken of. A similar alternation may be observed occasionally as a
teratological occurrence, though it is not easy to account for it.

[Illustration: FIG. 175.--Interrupted growth of Radish (from the
'American Agriculturist.')]

[Illustration: FIG. 176.--Interrupted growth in Apple.]

Fig. 175 shows an instance of the kind in a radish, and fig. 176 a
similar deformity in the case of an apple, the dilatation of the
flower-stalk below the ordinary fruit producing an appearance as if
there were two fruits one above another.

In leaves this peculiar irregularity of development is more common.

In some varieties of _Codiaeum variegatum_ the leaves resemble those of
_Nepenthes_, as the basal portion is broad, and terminates in a
projecting midrib destitute of cellular covering, and this again
terminates in a small pouch or pitcher. Somewhat similar variations may
be found in ferns, especially _Scolopendrium vulgare_.

Instead of the pouch there is formed sometimes in the plant last
mentioned a supplementary four-lobed lamina, the four lobes being in two
different planes, and diverging from the midrib, so that the section
would resemble [Symbol: Sideways X], the point of intersection of the x
representing the position of the midrib. This four-winged lamina is thus
very similar to the four-winged filaments described and figured at p.
289, and to the leaf-li