Supplementary observations on the fecundation of Orchideae and Asclepiadeae / by Robert Brown.

  • Brown, Robert, 1773-1858.
Date:
[1833]
Catalogue details

Licence: Public Domain Mark

Credit: Supplementary observations on the fecundation of Orchideae and Asclepiadeae / by Robert Brown. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    substance of the Ovulum; a fact, however, which I have not yet absolutely ascertained. Soon after the insertion of the Pollen tube, a change takes place in the appearance of the Ovulum, an internal body or nucleus becoming visible, with the upper attenuated extremity of which the point of insertion accurately corresponds. The Pollen tube, when thus inserted into the Ovulum, is not always absolutely destitute of granules; in some cases containing a few, which in size and form seem to be identical with those that completely fill it in its nascent state. But as such granules, at the period of insertion, are either very few in number, or apparently altogether wanting, I am still in- clined to consider them rather as furnishing the nourishment of the Tube than as being the essential agents in fecundation ; the really active particles in this function being probably much more minute. These supplementary observations may be concluded with the remark, that although the descent of Tubes derived from the Pollen into the cavity of the Ovarium, and their insertion into that point of the Ovulum where the Radicle of the future Embryo is seated, has been absolutely ascertained in several species of Orchideae and in one of Asclepiadeae, and probably will be found in the whole of these two extensive families, yet it does not follow that this descent and insertion of Tubes should be expected to extend to all Phaenogamous plants; for among these some structures of the female organ exist, which hardly admit of this ceconomy. London, July 31st, 1833.'