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XXXV. On the Organs and Mode of Fecundation in Orchidee 
and Asclepiadee. By Robert Brown, Esq., V.P.L.S., $c. 
Read November 1 and 15, 1831. 
Ix 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 Orchidez and Asclepiadew,—the two: 
families of phenogamous 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 sub- 
ject of Orchidez, I shall advert to a few other points of struc- 
ture in that natural order. 
ORCHID EE. 
The authors whose opinions or conjectures on the mode of 
impregnation in Orchidezw 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 cer- 
tain 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 impro- 
bable, 
