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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 sub- 

 ject of Orchideae, I shall advert to a few other points of struc- 

 ture in that natural order. 



ORCHIDE^. 



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 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. 



