264 OBSERVATIONS ON THE NATURAL FAMILY
where, though only five vessels are visible, they are erro- neously made to pass through the axes of the laciniae.
The only remaining author that notices these vessels is M. Mirbel, who in the second part of his valuable Elemens de Physiologie Vegetale et de Botanique, published in 1S15, introduces into his character of Compositae the fact of the laciniae of the corolla being furnished with marginal nerves. This observation, if not original, the author may have adopted either from my essay already quoted, of which he was in possession soon after its publication, or from M. Cassini's third memoir, which was read to the Institute of France six months after that essay appeared : but he could not have derived it from the passage in that author's second memoir, on which he rests his claim ; no notice being there taken of the disposition of vessels in the laciniae.
In M. Cassini's memoir expressly on the Corolla of Compositae, which was read to the Institute of France in December 1814, and of which an abstract, by the author 82] himself, is given in a late number of the Nouveau Bul- letin 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 tres simples qui le bordent d'un bout a l'autre des deux cotes, et confluent par consequent 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 Linnaeus himself in his Prolepsis Plantarum, and ably supported on different grounds by Mons. Decan- dolle in his excellent Theorie Elementaire 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 Linnaeus, without, how-
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