

would be superfluous to insist upon in this place. But in Cruciferce the 

 stigmata are opposite to the placentoe, terminating a sort of frame or replum, 

 the two sides of which are often connected by a membranous septum, on 

 the outside of which latter the ovula are arranged in a single row on each 

 side; so that in many of the more highly developed plants of the order there- 

 are four placentse opposed to each other by pairs, and forming the inner 

 edge of each side of the replum, which itself terminates in the stigmas. To 

 this replum is attached on each side a deciduous plate, or valve as it is 

 called, which has no vascular connexion with either the replum, stigmata, or 

 pedicel. In consequence of this singular arrangement of parts, it has been, 

 found extremely difficult to understand the exact nature of the Cruciferous 

 pistillum, or to reduce it to the rules which are known to govern the forma- 



tion of other compound pistilla. 



According to Mr. Brown, and after him to M. DecandoUe, the pistillum 

 of Cruciferse is to be understood to consist of two confluent ovaria, united 

 by their placentse, two lamellse from each of which project into the cavity 

 of the ovarium, and, meeting in the centre, coalesce and form the septum. 

 This, however, does not remove the difficulty of the stigmata being opposite 

 the placentae, instead of alternate with them. I am not aware that any 

 explanation of this point has been published by Mr, Brown ; but M. De- 

 candoUe {Theorie Elcmentaire, ed. 1. p. 133) accounts for it thus. He 

 assumes that there are several kinds of simple pistilla, some of which are not 

 to be found in an isolated state, but the possible existence of which he 

 conceives to be demonstrated by certain compound pistilla, that cannot be 

 reduced to their simplest state without the admission of such a position. 

 Among these supposititious simple pistilla is one called the Siliquelley 

 which is formed originally of three pieces, the two lateral producing 



« 



ovula 



termediate) 

 this description make up the fruit of Nymphaeaceae, 

 Papaveraceae, and Cruciferae. When two pistilla of this kind are united 

 by the external edge of their lateral pieces, they form those fruits which are 

 said to have intervalvular placentae ; each of these double placentae is elon- 

 gated into a style or stigma, simple in appearance, but in reality formed by 

 two half styles grown together." 



To maintain this theory, it is necessary to assume, in the first place, the 

 existence of a simple pistillum, of a structure not only entirely hypothetical, 

 but opposed to all we know of vegetable organization ; and, m the next 

 place, that the stigmata of the order, although so simple in appearance that 

 no trace whatever of composition can be found in them, are nevertheless 

 each composed of two half stigmata in a state of cohesion. 



To us this explanation has always been unsatisfactory. It was dif- 

 ficult to believe that rules of structure, well ascertained to be uniform 

 in other plants, should be deviated from in Cruciferas ; especially when 

 the irregularity observable in the arrangement of other parts of the flower 

 was taken into account; It always appeared more probable, that the 

 anomalous nature of the pistillum depended upon some irregularity cor- 

 responding to that of the stamens, than upon peculiar laws appertaining 

 to Cruciferae alone. 



This seems to be at length proved by Eschscholtzia, the fruit of which is 

 so similar to that of Cruciferae, that the uniformity of the laws under 

 which they are both formed is not likely to be disputed. In this plant the 

 pistillum IS unilocular, with four stigmata, of which the two opposite ones 



