352 



posterior ! 

 is in their 



BRASSICACE^. 



[Hypogynous Exogexs. 



iejials, the two paii's that remain belonging in fact to the foiu' petals. But it 

 fruit that the great peculiarity consists. 



Fig. CCXLIII. 



Since the placentae are opposite the lobes of the stigma in this 

 Order, it is difficult to reconcile the fruit with any general 

 theory of stmctm'e. Either it is in reality composed of fom* 

 carpels, two of which are abortive, as was fii'st suggested by me 

 in the Botanical Register, fol. 1168, or each of the two lobes 

 of the stigma is composed of two half lobes belonging to different 

 carpels, as in Poppy worts. In any view, the dissepiment which 

 cuts off the interior of the fruit into two cells must be considered 

 spurious, and a mere expansion of the placentae. 



The opinions of Botanists are much di\dded as to tliis matter ; 

 M. Kimth agrees ^vith me in considering the fmit composed of 

 four carpels. And a variety of evidence has gradually collected 

 in favour of this theory. M. Alph. De Candolle has shown that 

 the common Wall-flower is occasionally 4-celled {Monstruositts 

 Vegetaux, 15. t. 5.) There is a geims called Tetracellion, which 

 derives its name from the same cii'cumstance. Mr. Barker 

 Webb has published an account of a Canary shinib, named 

 Parolinia, in which the valves are constantly extended into 

 stigmas. But Mr. Howell {Ann. N. Hist. x. 254.) adopts 

 Brown's ^^ew of the subject, and, because of the supposed 

 affinity of Poppyworts, concludes that the fruit of Crucifers is 

 only composed of two carpels. He does not, however, offer any 

 dii'ect proof of the correctness of this opinion. 



Almost all Crucifers are destitute of bracts, and have the 



Fig. CCXLIII. — 1. Cheiranthus cheiri ; 2. its stigma ; 3. the same with one valve oflf ; 4. a cross sec- 

 tion of a seed ; 5. a diagram to illustrate the position of the parts of the tlower. 

 Fig. CCXLIV.— Fruits of Parolinia ornata, after Webb. 



Fig. CCXLIV. 



