NAMED RArrLESU. 379 



The structure now described actually exists in many [313 

 families of plants ; and the principal deviations from it 



ovaria agree, consists in their essential parts, namely, the pollen and ovula, 

 being produced on the margins of the modified leaf. 



_ In tlie AnthercB, whioli are seldom compound, and whose thecEe are usually 

 distinct, the marginal production of pollen is generally obvious. 



In the Ooaria, however, where, with very few exceptions, Ihe same arrange- 

 ment of ovula really exists, it is never apparent, but is always more or less 

 concealed either by the approximation and union of the opposite margins of 

 the simple pistillum, and of the compound when multilocular ; or in the 

 unilocular pistillum with several parietal placenlfe by the union of the corre- 

 sponding margins of its component parts. 



The few cases of apparent exception, where the ovula are inserted over the 

 whole or greater part of the internal surface of the ovarium, occur either in the 

 compound pistillum, as in Nymphaa and Nuphar; or in the simple pistillum, as 

 in Suiomea oi Richard; and in Lardizabalea, an order of plants sufficiently 

 distinct in this remarkable character alone, and differing also in the structure 

 of embryo and in habit, from IlenispermeiE, to which the genera composing it 

 (Lardizahala and Stauntonia) have hitherto been referred. 



The marginal production of ovula, though always concealed in the ordinary 

 or complete state of the Ovarium, not uufrequently becomes apparent where 

 its formation is in some degree imperfect, and is most evident in those devia- 

 tions from regular structure, where stamina are changed, more or less com- 

 pletely, into pistilla. Thus, in the case of the nearly distinct or simple pis- 

 tillum, it is shown by this kind of montrosity in Sempervmm Udorum; in the 

 compound multilocular pistillum, by that of Tropaolum majus; and in the com- 

 pound pistillum with parietal placentje, by similar changes in Cheiranthus Cheiri, 

 CocMearia armoracia, Papaver nudlcaule, and Salix oleifolia. 



In all the cases now quoted, and in several others with which I am ac- 

 quainted, it is ascertained that a single stamen is converted into a simple 

 pistillum, or into one of the constituent parts of the compound organ: a fact 

 which, in my opinion, establishes the proposed type of Ovarium. 



I liave entered thus slightly at present into the proof of this type, derived 

 from these deviations from regular structure, partly on account of an observa- 

 tion which I find in the second edition of the excellent TMorie MSmentaire de la 

 Boiauiqne of Professor De Candolle, to whom, in 1816, I had shown drawings 

 of most of the instances of monstrosity now mentioned. To these drawings, 

 and to my deductions from tliem with regard to the structure of pistillum, I 

 suppose the ingenious author alludes, in the passage in question. His views, 

 however, on this subject differ considerably from mine, which he does not seem 

 to have been aware were already published (Linn. Soc. Trans. I.e.) 



My second observation relates to the more important differences betvi'een the 

 antherse and ovaria, independent of their essential parts. 



In the Anthera the vascularity, with relation to that of the Leaf, may be said 

 to be diminished without being otherwise sensibly modified; the pollen is 

 formed in a cellular substance apparently destitute of vessels ; and is always 

 produced internally, or under the proper membrane of the secreting organ. 



In the Ovarium, on the other hand, the vascularity, compared with that of 

 the Leaf, is in general rather modified 'than diminished; the principal vessels 

 oeeupying the margins or lines of production, and giving off branches towards 

 the axis, whose vascularity is frequently reduced. The ovula constantly arise 

 from vascular cords, and, with reference to the supposed original state of the 

 ovarium, are uniformly produced externally ; though by the union of its parts, 



