that which
occurs normally in the allied genus _Mozinna_. _Reseda luteola_
occasionally occurs with two carpels only, while Aconites, Delphiniums,
Nigellas, and Paeonies frequently experience a like diminution in their
pistil.

In a flower of _Papaver Rhaeas_ the writer has recently met with an ovary
with four stigmas and four parietal placentae only, and to Mr.
Worthington Smith he is indebted for sketches of crocus blooms with two,
and in one instance only a solitary carpel.

Moquin cites the fruit of a wild bramble (_Rubus_) in which all the
little drupes which go to make up the ordinary fruit were absent, except
one, which thus resembled a small cherry. In _Crataegus_ the pistil is
similarly reduced to a single carpel, as in _C. monogyna_.

The writer has on more than one occasion met with walnuts (_Juglans_)
with a single valve and a single suture.[472] If the ovary of _Juglans_
normally consisted of two valvate carpels, the instances just alluded to
might possibly be explained by the suppression of one carpel, but the
ovary in _Juglans_ is at first one-celled according to M. Casimir de
Candolle.

Among monocotyledons _Convallaria majalis_ may be mentioned as very
liable to suffer diminution in the number of its carpels, either
separately or in association with other changes.[473]

=Meiophylly of the flower as a whole.=--In the preceding sections a
reduction in the parts of each individual whorl has been considered
without reference to similar diminution in neighbouring verticils. It
more commonly happens, nevertheless, that a defect in one series is
attended by a corresponding imperfection in adjoining ones. Thus
trimerous fuchsias and tetramerous jasmines may frequently be met with,
and Turpin describes a tetramerous flower of _Cobaea scandens_. Perhaps
monocotyledonous plants are more subject to this numerical reduction of
the parts of several verticils than are other flowering plants. Thus, in
both _Lilium lancifolium_ and _L. auratum_ the writer has frequently met
with pentamerous flowers. In _Convallaria maialis_ a like deviation not
unfrequently occurs.[474] M. Delavaud has recorded a similar occurrence
in a tulip.[475]

Dimerous crocuses may also sometimes be met with. In one flower of this
nature the segments of the perianth were arranged in decussating pairs,
and the four stamens were united by their filaments so as to form two
pairs.

M. Fournier mentions something of the same kind in the flower