ments of the
perianth may be subjected to hypertrophy; thus, the utricle of _Carex
vulpina_ may frequently be observed to attain four or five times its
usual size, the contained ovary remaining unaffected. This condition is
generally the result of insect puncture. The growth of parasitic fungi
will produce a similar result, as is often seen in the common shepherd's
purse, _Thlaspi bursa pastoris_, and other _Cruciferae_. The perianth of
_Rumex aquaticus_ has been also observed to be occasionally
hypertrophied in conjunction with a similar condition of the pistil and
with atrophy of the ovules.

Moquin relates having found flowers of _Salsola Kali_ and of
_Chenopodium murale_ in which some of the segments of the perianth were
five or six times larger than they should be.

[Illustration: FIG. 205.--Hypertrophy of the perianth in _Cocos
nucifera_.]

The adjoining woodcut represents a singular condition of some cocoa-nuts
in the Kew Museum, the appearance of which is due apparently to an
hypertrophied condition of the segments of the perianth, which have not
only increased in length as the central nut has ripened, but have
developed in their tissues that fibrous tissue which ordinarily is found
in the pericarp only. This view of the structure of these nuts is borne
out by the fact that, under normal circumstances, the base of the
perianth contains a considerable amount of fibrous material. In the
present case this has increased to such an extent that the fruit appears
surrounded by a double husk, by an inner one as usual, and by an outer
six-parted one.

It will be remembered that in some of the _Cinchonaceae_, e.g.
_Mussaenda_, _Pinckneya_, _Calycophyllum_, one or more of the calycine
lobes are normally dilated and petaloid, the others remaining small and
comparatively inconspicuous. Inequality in size is, indeed, a common
occurrence in the sepals of many natural orders--_Polygalaceae_,
_Leguminosae_, _Labiatae_, &c. The flowers of a rose are mentioned by
Moquin as having presented an enlargement of the calyx without any other
alterations in form. Schlechtendal has noticed the same thing in
_Papaver Rhoeas_, Reichenbach in _Campanula persicifolia_, and A. de
Candolle in _C. Rapunculus_. M. Brongniart also has recorded[498] a
remarkable variety of _Primula sinensis_ cultivated in the Jardin des
Plantes at Paris, wherein the calyx is enormously developed. MM.
Fournier and Bonnet have described flowers of _Rubus_ with hy