Page:Transactions of the Linnean Society of London, Volume 12.djvu/110

82 number of the Nouveau Bulletin des Sciences, the disposition of vessels in the corolla is expressed in the following terms:

"Chacun des cinq petales dont se compose la corolle est muni de deux nervures très simples qui le bordent d'un bout à l'autre des deux côtés, et confluent par conséquent au sommet."

On this statement I have several remarks to offer. And first, I object to its hypothetical language. Whatever opinion may be formed of the theory here adopted by the author, namely, that every monopetalous corolla is in reality composed of several confluent petals; a theory first proposed by Linneus himself in his Prolepsis Plantarum, and ably supported on different grounds by Mons. Decandolle in his excellent Théorie Elémentaire de la Botanique; I can see no advantage in adopting its language in stating a fact of this kind, especially if proposed as a practical character.

For my own part, I consider this opinion as correct in the sense in which it was held by Linneus, without, however, connecting with it the ingenious hypothesis of M. Decandolle, namely, that petals are only modified stamina. It remains to be seen on what ground M. Cassini has adopted this theory, as proposed by M. Decandolle, for Compositæ, the only family which seems to present a very important objection to it, in having its principal, and in the greater part of the order its only, vessels occupying the lines of junction of the supposed united petals.

To adapt this disposition of vessels to the theory, M. Cassini is obliged to subdivide their apparently simple trunks; a division, however, which may be regarded as entirely hypothetical. From the observations I have made on the subject, I have no doubt that these trunks are equally simple with the secondary nerves when present, or with the primary in other families. I find them to consist of two kinds of vessels, the spiral and ligneous. Of the spiral vessels