ecium.=--Moquin[410] remarks that, as the
pistils are, generally speaking, more or less subject to pressure, owing
to their central position, and it may be added owing to their later
development, than the other parts of the flower, they are more subject
to suppression than to multiplication; nevertheless, augmentation in the
number of carpels does occasionally take place, especially when the
other parts of the flower are also augmented in number. Sometimes this
increase in the number of carpels is due to pure multiplication, without
any other change. At other times the increase is due to a substitution
of stamens or other organs for carpels (see Substitutions). In other
cases the augmentation seems to be due to the development of parts
usually suppressed; for instance, in _Antirrhinum_, where there are
usually only two carpels present, but where, under peculiar
circumstances, five may be found--thus rendering the symmetry
complete.[411] In _Papilionaceae_, wherein usually only one carpel is
developed, we occasionally find two, or even more, as in _Wistaria_,
_Gleditschia_, _Trifolium_, &c. In _Prunus_ and _Amygdalus_ from two to
five carpels are occasionally to be found,[412] in _Mimosa_ five, in
_Umbelliferae_ three to five; in some composites, _e.g._ _Spilanthes_,
five carpels have also been noticed; in _Cruciferae_ three and four, in
grasses three.[413] The double cocoa-nut affords an illustration of the
development of two carpels out of three, one only generally arriving at
perfection. Triple nuts (_Corylus_) also owe their peculiarity to the
equal development of all three carpels which exist in the original
flower, but of which, under ordinary circumstances, two become abortive.
It is necessary, however, to distinguish these cases from those in which
two embryos are developed in one seed.

The following list may serve to show in what genera this change has been
most frequently noticed, and it may be said in general terms that
_Cruciferae_, _Umbelliferae_, and _Liliaceae_, are the orders most
frequently affected. Cases of peloria are not included in the subjoined
list.

Nigella.
Aquilegia.
Paeonia!
Delphinium!
Iberis.
Diplotaxis.
Lunaria.
Ricotiana.
Octadenia.
Draba!
Lepidium.
*Cheiranthus!
Dianthus.
Brassica!
Parnassia.
*Acer!
Ptelea.
Citrus!
Philadelphus.
Prunus!
Amygdalus!
Crataegus!
Fuchsia!
Trapa!
Cassia.
Cercis.