But in this place it is only necessary to allude to deviations from the number of carpels that are ordinarily found in the particular species under observation. As illustrations the following may be cited:--_Arenaria tetraqueta_, which has normally three styles, and a six-valved capsule, has been seen with two styles, and a four or five-valved capsule. Moquin relates an instance in _Polygala vulgaris_ where there was but a single carpel, a condition analogous to 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 of an _Iris_.[476]