f
(generally) rudimentary organs very different in their morphological
nature and significance, and also in their functions. Some are truly
glandular or secreting organs, while others have no visible office.
Anything like a complete account of these structures would be out of
place, and reference is only made to them here on account of the
occasional existence of intermediate forms, which throw light on the
morphological significance of these structures. Thus, in _Passiflora_
and _Viburnum Opulus_, the so-called glands on the sides of the petiole
appear to represent leaflets, and are not unfrequently developed as
such.

M. Dunal observed a flower of _Cistus vaginatus_ in which some of the
stamens were replaced by an hypogynous disc.[547] Moquin has seen
similar instances in the flowers of a Rose, _Hypericum_, and Poppy.

M. Planchon[548] gives an account of some very curious malformations in
_Drosera intermedia_, which go to show that the ovules are homologous
with the glandular hairs on the margins of the leaves of these plants,
an opinion corroborated by the researches of MM. Groenland and
Trecul.[549]

Dr. Hooker shows that the pitcher of _Nepenthes_ is due to a
modification of a gland placed at the extremity of the midrib.[550]

=Formation of tendrils.=--These are of very varied morphological import;
sometimes they are degenerated peduncles, as in passion-flowers, or
vines; at other times they are of foliar origin; or, again, they may
proceed from the segments of the perianth, as in _Hodgsonia_ and some
other cucurbitaceous plants. From their very different origin in
different plants it is necessary to study the development in each case,
and not apply to the generality what may be peculiar to one. In any case
this formation in question generally belongs more to general morphology
than to teratology.[551]

Kirschleger, however, has recorded the existence of a cirrhose sepal in
_Cucurbita Pepo_.[552]

FOOTNOTES:

[547] 'Consid. Org. Fleur.,' p. 44, pl. ii, fig. 23.

[548] 'Ann. Sc. Nat.,' 3 ser., Bot. ix, pl. 6, ff. 1, 2.

[549] 'Ann. Sc. Nat.,' 3 ser., Bot. 1855, pp. 297, et 303.

[550] 'Trans. Linn. Soc.,' xxii, p. 415.

[551] See Darwin, "On Climbing Plants," 'Journal of Linnean Society,'
vol. ix, p. 1.

[552] 'Flora,' 1845, p. 615.

GENERAL CONCLUSIONS.

At the end of many of the preceding sections, and whenever the
requirements of the case demanded it, a brief summary of the main facts