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 6 ON THE PROTEACE^ OF JUSSIEU.

the plants of Madagascar and the Isles of France and Bourbon.

The bursting of the antherae has, it is true, been gene- rally observed, and many of its most unusual modes have been introduced into the characters of genera ; but the ex- amination of these organs, at a still earlier period, has been universally neglected ; and hence the very imperfect know- ledge which, even now, is possessed of their real nature in two of the most remarkable families of plants, the Orchideae and Asclepiadege.

Examples of the great advantage of observing the antherae in this early stage will hereafter be given in my general re- marks on the order which is the proper subject of this essay. But I trust I shall be pardoned for here introducing some account of their structure in Asclepiacleae, as it will enable me not only to bring forward the most striking proof of the importance of this consideration with which I am acquainted, but also, as I apprehend, to decide a question which has long occupied, and continues to divide, the most celebrated botanists.

The point in dispute is whether this order, comprehend- ing Asclepias, Cynanchum, Pergularia, Stapelia, and several genera, at present confounded with these, ought to be re- ferred to Pentandria or Gynandria, and, if to the latter, whether the antherae are to be considered as five or ten ; all of which opinions have had advocates of the greatest name in the science.

According to Linnaeus, Jussieu, and Richard, they belong to Pentandria.

Linnaeus has assigned no reason for his opinion, which, however, it appears he retained after he became acquainted with the observations of Jacquin and Rottboell ; but it is 17] probable he was induced to adopt it more from the con- sideration of the close analogy these plants have with the manifestly pentanclrous Apocineae, than from regarding them as strictly referable to this class ; for, in his natural generic characters of Asclepias and Pergularia, he very clearly de- scribes both these genera as gynandrous.

Jussieu has entered more fully into the subject, but seems

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