82 Mr. Brown's Observations on the 



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 tres simples qui le bordent d'un bout a I'autre 

 des deux c6tes, 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 con- 

 fluent petals; a theory first proposed by Linneus himself in his 

 Prolepsis Plantarum, and ably supported on different grounds by 

 Mons. Decandolle in his excellent Theorie Elemcntaire do 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. Decan- 

 dolle, for Composita?, the only family A^'hich 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 con- 

 sist of two kinds of vessels, the spiral and ligneous. Of the spiral 



vessels 



