we may say that an hypertrophied organ is
one which, from some cause or other, attains dimensions which are not
habitual to the plant in its usual, healthy, well-formed state.

It will be seen that under this general head of hypertrophy, increase of
size, however brought about, is included; thus, not only increase in
length, but also in thickness; alterations of substance or consistence,
no less than of dimensions, are here grouped together. The alterations
of consistence resulting from an inordinate development of cellular,
fibrous, or ligneous tissue, are, of course, strictly homologous with
the similar changes which occur, under ordinary circumstances, during
the ripening of fruits or otherwise.

Hypertrophy, whatever form it may assume, may be so slight as not
perceptibly to interfere with the functions of the part affected, or it
may exist to such an extent as to impair the due exercise of its office.
It may affect any or all parts of the plant, and is generally coexistent
with, if not actually dependent on, some other malformation. Thus, the
inordinate growth of some parts is most generally attended by deficiency
in the size and number of others, as in the peripheral florets of
_Viburnum_ or _Hydrangea_, where the corollas are relatively very large,
and the stamens and pistils abortive.

CHAPTER I.

ENLARGEMENT.

A swollen or thickened condition (_renflement_) is usually the result of
a disproportionate formation of the cellular tissue as contrasted with
the woody framework of the plant. We see marked instances of it in
cultivated carrots and turnips, the normal condition of the roots or
root-stocks in these plants being one of considerable hardness and
toughness, and their form slender, tapering, and more or less branched.

The disproportionate development of cellular tissue is also seen in
tubers and bulbs, and in the swollen stems of such plants as
_Echinocactus_, _Adenium obesum_, some species of _Vitis_, &c. So, too,
the upper portion of the flower-stalk occasionally becomes much
dilated, so as ultimately to form a portion of the fruit. But it is not
necessary to give farther illustrations of this common tendency in some
organs to become hypertrophied. As a result of injury from insects or
fungi, galls and excrescences of various kinds are very common, but
their consideration lies beyond the scope of the present work.

[Illustration: FIG. 200.--_Pelargonium_, one branch of which was
hypertroph