15 



their great peculiarity consists. I transcribe the following observations upon 

 this subject from the Botanical Register, fol. 1168, in which I have entered 

 in some detail into the inquiry. 



" It is well known, that in regularly-formed fruits the style or stigma 

 universally and necessarily alternates with the placenta, for reasons which it 

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

 stigmata are opposite to the placentse, 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 placentae 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 pistil- 

 lum, or to reduce it to the rules which are known to govern the formation of 

 other compound pistilla. 



" According to Mr, Brown, and, after him, to M. Decandolle, the pis- 

 tillum of Cruciferae is to be understood to consist of two confluent ovaria, 

 united by their placentae, two lamellae 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- 

 candolle ( Theorie EUmentaire, ed. 1. p. 1 33) 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 Siliquelle, ' which is formed 

 originally of three pieces, the two lateral producing ovula on their inner 

 surface, and the outer (intermediate) one bearing no ovula ; pistilla of this 

 description make up the fruit of Nymphaeacese, Papaveraceae, and Cruciferse. 

 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 elongated 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 hypothe- 

 tical, but opposed to all we know of vegetable organisation ; and, in 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 difficult 

 to believe that rules of structure, well ascertained to be uniform in other 

 plants, should be deviated from in Cruciferae, especially when the irregularity 

 observable in the arrangement of other parts of their flower was taken into 

 account. It always appeared more probable, that the anomalous nature of 

 the pistillum depended upon some irregularity corresponding 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 are smaller 



