IN ORfflTDKE AND ASCLEPIADEvE. 541 



course of the tubes is not at all impeded, they arc very 

 nearly or altogether straight. 



The two most im[)()rtaut faets stated in tlie present 

 eonununication are ; first, the |)roduction of tubes not 

 directly emitted from the grains of pollen, but apparently 

 generated by them ; and, secondly, the introduction of one 

 nr S(Hnetimes more than one of those tubes into the fora- 

 men of the ovulum, the point corresponding with the 

 I'adicle of the future embryo. 



11ie piincipal points remaining to be examined, and 

 which we may hope, by careful investigation, to ascertain, 

 are the precise state of the ovulum at the moment of its 

 contact Avith the tube, and the immediate changes conse- 

 quent to that contact. 



Supplementary Note. [7u 



Since the paper on fecundation in Orchideae and Ascle- 

 i)iadeae was read before the Society, and a Pamphlet con- 

 taining all its more important statements was distributed 

 in the beginning of November, 1S31,^ two essays have ap- 

 peared on the same subject. The first on both families by 

 M. Adolphe Brongniart, in the numbers of the Annates ties 

 Sciences Natiirelles for October and November, 1S31, but 

 which were not published until January and February, 

 1832; the second, by Dr. "Ehrenberg, on Asclepiadeae 

 alone, in the Transactions of the Royal Academy of Sciences 

 of Berlin, before which it was read in November, 1831. 



M. Brongniart's statements respecting Orchideae to a 

 great extent agree with those of my essay. They differ, 

 however, in the following important points : 



1st, He does not seem to be aware of the operation of 

 insects in the fecundation of this family. 



."2ndly, He considers tiie mucous cords in the cavity of 

 the ovarium (first seen by M. du Petit Thouars, with 

 whose o])servations he seems to be entirely unac(iuainted), 



' I may also refer to an excellent abstract of the Taper which appeared ou 

 the 1st of Dcccuiber, 1$31, iu the IMiilos. Mag. and Annals of riiilosophy. 



