Observations on the organs and mode of fecundation in Orchideae and Asclepiadeae

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1833 Excerpt: ... XXXV. On the Organs and Mode of Fecundation in Orchidea and AsclepiadecE. By Robert Brown, Esq., V.P.L.S., $c. Read November 1 and 15, 1831. In the Essay now submitted to the Society, my principal object is to give an account of some observations, made chiefly in the course of the present year, on the structure and economy of the sexual organs in Orchideae and Asclepiadeae,--the two families of phaenogamous plants which have hitherto presented the most important objections to the prevailing theories of vegetable fecundation. But before entering on this account, it is necessary to notice the various opinions that have been held respecting the mode of impregnation in both families: and in concluding the subject of Orchideae, I shall advert to a few other points of structure in that natural order. ORCHIDE.E. The authors whose opinions or conjectures on the mode of impregnation in Orchideae I have to notice, may be divided into such as have considered the direct application of the pollen to the stigma as necessary: and those who,--from certain peculiarities in the structure and relative position of the sexual organs in this family,--have regarded the direct contact of these parts as in many cases difficult or altogether improbable, bable, and have consequently had recourse to other explanations of the function. In 1760, Haller, the earliest writer of the first class, in describing his Epipactis, states that the antherae or pollen masses, after leaving the cells in which they are originally inclosed, are retained by the process called by him sustentaculum, the rostellum of Richard, from which they readily fall upon the stigma. He adds, that both in this genus and in Orchis the stigma communicates by a fovea or channel with the ovarium. But as in 1742 he correctl...