Linmean Society. 437 



tends that both chains were elevated posterior to the formation of the 

 conglomerate and older diluvium, and therefore that their periods of 

 elevation are identical. 



LINN^AN SOCIETY. 



Nov. 1 and 15. — A Paper was read on the Sexual Organs and 

 mode of Impregnation in Orchidece and Asclepiadece. By R. Brown, 

 Esq., V.P.L.8., &c. &c. 



Mr. Brown's principal object in this paper is to detail some obser- 

 vations on the structure and oeconomy of the fecundating organs in 

 these families, made by him chiefly in the present year. They have 

 hitherto presented the most important objections to the prevailing 

 theories of vegetable fecundation : but Mr. Brown thinks we are now 

 as far advanced with respect to this function in these families, as in 

 any other tribe of Phsenogamous plants ; and that upon the general 

 problem of generation, additional light is more likely to be derived 

 from them than any other part of the vegetable or animal kingdom. 



Orchidece. — Two opinions have been entertained as to the mode of 

 impregnation in this family. Haller, Adanson, Curtis, C. K. Spren- 

 gel, J. K. Wachter, Schkuhr, Swartz, Salisbury, and Treviranus 

 considered the direct application of the pollen to the stigma as essen- 

 tial to fecundation : while others, as Linnseus, Schmidel, Koelreuter, 

 Stokes, Batsch, Richard, Du Petit Thouars, Link, Lindley, Bauer, and 

 Mr. Brown himself, from the peculiarities observable in the structure 

 and relative position of the sexual organs, have considered the direct 

 contact of the pollen mass and stigma as improbable, and have con- 

 sequently had recourse to other explanations of this function. 



Wachter in 1/99 was the first who succeeded in impregnating an 

 orchideous plant by applying the pollen to the stigma, — a result 

 which was confirmed in 1804 by Salisbury, and twenty years after 

 by Treviranus. 



These observers have sufficiently proved that impregnation is ac- 

 complished by the direct application of pollen to stigma : but no sub- 

 sequent phenomena resulting from the action of the stigma on the 

 pollen is noticed. 



Those authors who conceived that the pollen mass could not come 

 into direct contact with the stigma, have attempted to explain the fe- 

 cundation of Orchidece in various ways. 



Batsch in 1791 supposed that the only way in which the pollen 

 could act on the ovarium in Ophrydece was by the retrogradation of 

 the impregnating power through the caudicula to the gland beneath 

 it ; and this opinion was also that of Richard, who applied it to the 

 whole order, and was entertained by Mr. Brown in 1810. It was 

 also the opinion of Mr. Bauer, to whom it appears to have occurred 

 as early as I 792. 



The opinion of Du Petit Thouars was peculiar. He considered that 

 the glutinous substance connecting the grains of pollen was the fe- 

 cundating matter ; that tiie elastic pedicel of the pollen mass, not 

 formed before expansion, consisted of this gluten ; and that in tlie 

 expanded flower, the gluten which Iia." escaped from the pollen is, in 



all 



