330 Mr. Griffith on the Root-Parasites referred to Rhizantheae, 



of the placental margins of the carpellum. Such an origin is very compatible 

 with the appearances of many linear stigmata, which present a sulcus along 

 the centre ; with those of some monocarpellary Urticece, which have two obvious 

 stigmata; and indeed, admitting degrees of cohesion by no means unusual in 

 other parts of the flower, may be extended perhaps to all the stigmata I have 

 examined. 



M. Schleiden* would appear to refer the origin of the conducting tissue to 

 the epidermis of the upper surface of the leaf. 



From the stigma having been generally found to present definite relations 

 with the style of its carpellum, has arisen its importance in determining the 

 composition of the compound ovarium. But these ordinary relations, from 

 which alone its practical character arises, may be obscured by several causes ; 

 as the separation of parts usually cohering ; the cohesion of parts ordinarily 

 distinct; the division of the merely stigmatic part of each style; the division 

 of the style of the simple carpellum. 



The stigmata of each carpellum may be distinct from each other, or from 

 those of the next carpella. The only strong tendency to this, I know of, occurs 

 in Euhalus, in which the distinction of the stigmata is accompanied by a 

 distinction of the placentae. The result is obvious if applied to a multilocular 

 compound pistillum. 



Many botanists appear to me to have lost sight of the possibility of an ad- 

 hesion taking place between stigmatic surfaces ordinarily distinct, similar to 

 that which is considered to cause the loculicidal dehiscence of fruits ; whereby 

 the stigmata, so resulting, instead of having an obvious correspondence with 

 the dorsa of the styles, appear actually to alternate with them. Such an ex- 



Dr. Wight', is not alluded to by Mr. Brown. Dr. Wight's hypothesis does not appear to me to be 

 tenable ; for it reverses, without any ascribed cause, the very general law regarding the relations of the 

 surface of the lamina of the leaf to the axis. It is also, I think, contradicted by the examination of 

 the very young states of the ovarium of Coccinea indica, in which there are evidently three ordinarily 

 compound parietal placentae, and also by the placentation of the fully-formed ovarium of Zanonia, the 

 structure of which appears to me to be conclusive on this point. 

 * Op. cit. p. 183. 



' Madras Journal of Literature and Science, no. 28, 1840, p. 43. 



