the polliniferous cells are at the same time persistent, as in certain species of Viscum.
The deviations from the regular mode of bureting are also numerous; in some cases consisting either in the aperture being confined to a definite portion, generally the upper extremity, of the longitudinal furrow, as in Dillenia and Solanum; in the apex of each theca being produced beyond the receptacle of the pollen into a tube opening at top, as in several Ericinæ; or in the two thecæ being confluent at the apex, and bursting by a common foramen or tube, as in Tefratheca. In other cases a separation of determinate portions of the membrane takes place, either the whole length of the theca, as in Hamamelideæ and Berberideæ; or corresponding with its subdivisions, as in several Laurinæ; or lastly, having no obvious relation to internal structure, as in certain species of Rhizophora.
The regular structure may also be altered or disguised by the union of two or more stamina; the thecæ of each anthera either remaining distinct and parallel, as in Myristica, Canella, and in several Aroideæ; being divaricate and united, as in Cissampelos; or absolutely separate, by division of the filament, as in Conospermum and Synaphea.
It is unnecessary for my present purpose to enter into a more minute account of the various structures of stamina, most of which appear to me easily reducible to the type here assumed.
The precise relation of the anthera of Rafflesia, however, to this type is so far from being obvious, that at least three different opinions may be formed respecting it.
According to one of these, each actual anthera would be considered as composed of several united stamina. But in adopting this opinion, which is suggested solely by the existence and disposition of the cells of the anthera, it seems also necessary to consider the apparently simple flower of Rafflesia as in reality compound, and analogous to the spike of an Aroidea; the pistilla, if present, being consequently to be looked for not in the centre but in the circumference. On attending, however, to the whole external structure of
