vestments become more or less atrophied, or are even
more frequently entirely suppressed, as is also the nucleus.

In other cases, a simple arrest of development takes place; the ovule,
for instance, which should be anatropal, remains straight, while the
integuments, checked in their development, form imperfect sheaths from
which the shrivelled nucleus protrudes.

=Depauperated Ferns.=--The preceding illustrations have been taken from
flowering plants chiefly, but a similar defective development is
manifested in cryptogamous plants. The contraction and imperfect
development of the fronds of some varieties of ferns, hence called
depauperated, may receive passing notice, as also the cases in which the
sori or clusters of spore cases are denuded of their usual covering,
owing to the abortion or imperfect development of the indusium, as in
what are termed exindusiate varieties.[543]

=General remarks on abortion, coincident changes, &c.=--Reference has
already been made, while treating of hypertrophy, suppression, &c., to
certain other changes affecting the flower at the same time. Atrophy of
one organ or set of organs, for instance, is frequently accompanied by a
compensating hypertrophy or by an increased number of other parts. In
the feather-hyacinth, _Muscari comosum_, var., _monstrosum_, the absence
of flowers is compensated for by the inordinate formation of brightly
coloured threads which appear to be modified pedicels (see pp. 347,
348); so also in the wig plant, _Rhus Cotinus_. So the atrophy of the
stamens, in some flowers, is coincident with the hypertrophy of the
pistil. Thus, Unger, 'Denkschr. d. Kais. Acad. der Wissensch. Math. Nat.
Classe,' Mai 25, 1848, p. 103, tab. ix, describes a case wherein the
corolla and stamens of _Desmodium marylandicum_ were atrophied, while
the calyx and legume, on the other hand, were hypertrophied.

Fusion of the members of one whorl with one another, or with the
components of an adjacent series, often entails atrophy or suppression,
either in the united organs themselves, or in adjacent ones. A
foliaceous condition of the outer portions of a flower is very generally
attended by atrophy or complete suppression of the inner portions.

From this point of view the observations of Morren[544] on the different
degrees of atrophy up to complete suppression, observable in the flowers
of _Bellevalia comosa_, are of importance. According to this observer,
the most highly differentiate