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 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 the 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 the 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.

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