254 Mr. J. W. Howell on the Capsule of Papaveraceae, fyc. 



vascular areolae. Thus far, then, the two highest botanical 

 authorities agree in considering the silique to be composed of 

 two carpels, and such is really the case, — but, as Lindley justly 

 remarks, ' Int. Nat. Syst./ ed. 1, " This does not remove the 

 difficulty of the stigmata being opposite the placentas, instead 

 of alternate with them." To meet this difficulty, DeCandolle 

 (according to Lindley) proposed a theory, which, in addition 

 to some untenable assumptions, included the supposition of 

 each stigma being composed of two lateral halves, in a state 

 of cohesion, each half being the continuation of the lamella of 

 the placenta of the corresponding carpel. As, at the time this 

 theory was proposed, the assumption here quoted was alto- 

 gether gratuitous, there being no actually observed structures 

 then known to corroborate it, Lindley (Op. cit. and ' Bot. 

 Register/ fol. 1168 with diagrams) proposed another, founded 

 on the structure of Eschscholtzia, wherein he concludes that 

 the silique of Cruciferce is formed of four carpels, instead of 

 two ; that the alternate ones are reduced in lateral extent, but 

 have their placentas perfect ; and that the stigmas of the si- 

 lique belong to them, while the two remaining carpels have lost 

 their placentas and stigmas, and are thus reduced to the form 

 of valves. In this manner, the correspondence of the stigmas 

 with the parietal placentas was shown not to be an exception 

 to the law which expresses their necessary alternation, but to be 

 in strict conformity with it, the correspondence of the stigmas 

 and placentas being only apparent, not real. The object in 

 forming this ingenious though complex theory was to avoid De- 

 Candolle's hypothetical assumption of the compound nature 

 of the stigma, which Lindley rejected, notwithstanding that 

 Brown considered its truth to be rendered probable by the 

 evidence of some monstrous varieties of the siliquose capsule. 

 As, however, the admission of the compound structure of the 

 stigma meets all the difficulties of the case, and explains the 

 apparently anomalous arrangement of parts in an easy and 

 concise manner, and as of two proposed theories we are war- 

 ranted in selecting that which is most simple, I have much 

 satisfaction in being the first to adduce proof, derived from 

 actual structures, that the individual stigmas of syncarpous 

 capsules are occasionally compounded of the adjacent lateral 

 halves of contiguous carpels. Hence I conclude, with Brown 

 and DeCandolle : — 



1st. That it is most probable that the silique of Crucifera 

 is composed of two carpels, whose inflected margins form two 

 bi-lamellate parietal placentas ; and that the apparently ano- 

 malous disposition of the stigmas arises from their being 

 formed of two lateral halves, each of which belongs to the 

 corresponding subjacent carpel. 



