]1 
as to the real structure of this order, and, consequently, as to its atHnities. 
This has arisen chiefly from the anomalous nature of the embryo, which 
is not naked, as in most plants, but enclosed in a membranous sac or bag. 
By some, among whom was the late L. C. Richard, this sac or bag was con- 
sidered a cotyledon, analogous to that of grasses, and enveloping the plumule; 
and hence the order was referred to Endogens, or Monocotyledons, and 
placed in the vicinity of Hydrocharacese. By others, at the head of whom 
are Messrs. Mirbel and De Candolle, the sac is considered a membrane of 
a peculiar kind ; and what Richard and his followers denominate plumule, 
is for them a 2-lobed embryo, wherefore they place the order in Exogens, 
or Dicotyledons. I do not think it worth citing all the arguments that have 
been adduced on each side the question, as botanists seem now to be gene- 
rally agreed upon referring Nymphaeacese to Dicotyledons. I observ'e more- 
over that Von Martins who once adhered to the opinion that Nymphaeaceae 
are monocotyledonous, and nearly related to Hydrocharaceae, (see Hortus 
Regius Monacensis, p. 25.) now places the order in its true position near Ra- 
nunculaceae (see Conspectus, No. 188.) Those who are curious to investigate 
the subject are referred to De Candolle’s Memoir, in the first volume of the 
Transactions of the Physical and Natural History Society of Geneva. In this 
place it will be sufficient to advert briefly to the proof that is supposed to 
exist of Nymphaeaceae being Dicotyledons. In the first place, the struc- 
ture of the stem is essentially that of Exogens, according to Mirbel’s examina- 
tion of the anatomy of Nuphar luteum, in the Annates du Museum, vol. 16, 
p. 20 ; and of Nelumbium, the close affinity of which with Nymphaeaceae no 
ofie can possibly doubt, in the same work, vol. 13, t. 34. In both these 
plants the bundles of fibres are described as being placed in concentric circles, 
the youngest of which are outermost; but they aU lie among a great quantity 
of cellular tissue : between each of these circles is interposed a number of air- 
cells, just as is found in M)Tiophyllum and Hippuris, both undoubted Dicoty- 
ledons in the opinion of every body except Link, who refers the latter to 
Endogens (see Gewdchsk, 6, p. 288). Secondly, the leaves are those of Dico- 
tyledons, and so is their convolute vernation, which is not known in Monoco- 
tyledons, and their insertion and distinct articulation with the stem. Thirdly, 
the flowers of Nymphaeaceae have so great an analogy generally with Dico- 
tyledons, and particularly with those of Magnoliaceae, and their fruit with 
Papaveraceae, that is difficult to doubt their belonging to the same group. 
Fourthly, the reasons which have been offered for considering the embryo 
monocotyledonous, hpwever plausible they may have appeared while we were 
unacquainted with the true structure of the ovule of other plants, have no 
longer the importance that they were formerly supposed to possess. The sac, 
to which I have already alluded, to which so much unnecessary value has been 
attached, and which was mistaken for a cotydelon by Richard, is no doubt 
analogous to the sac of Saururus and Piper, and is nothing more than the 
remains of the innermost of the membranous coats of the ovule, usually indeed 
absorbed, but in this and similar cases remaining and covering over the 
embryo. Brown {Appendix to King's Voyage) considers it the remains of the 
membrane of the amnios. De Candolle assigns a further reason for consider- 
ing Nymphaeaceae Dicotyledons, that they are lactescent, a property not 
known in Monocotyledons. But in this he is mistaken ; Limnocharis, a genus 
belonging to Butomaceae, is lactescent. It must moreover be observed, that 
the arrangement of the woody matter of Nuphar luteum is far less obviously 
exogenous than would be supposed from the manner in which it is described 
by Mirbel. 
Independently of the peculiarities to which I have now alluded, this order 
