“< =, 7 
THEORETICAL STRUCTURE OF THE FLOWER. 3849 
considered only as homologous parts to leaves, or parts of the 
same fundamental nature, that is, as well stated by Lindley, 
‘constructed of the same elements arranged upon a common 
plan, and varying in their manner of development, not on 
account of any original difference in structure, but on account 
of special, local, and predisposing causes: of this plan the leaf 
is taken as the type, because it is the organ which is most 
usually the result of the development of those elements,—is 
that to which the other organs generally revert, when from any 
accidental disturbing cause they do not sustain the appearance 
to which they were originally predisposed,—and, moreover, 
is that in which we have the most complete type of organisa- 
tion,’ and, we may add, is that which can always be distinctly 
traced by insensible gradations of structure into all the other 
arts. 
i Having first defined the general nature of the doctrine of 
Morphology, or that doctrine which investigates the various 
alterations of form, and other characters, which the different 
parts of plants undergo in order to adapt them to the several 
purposes for which they were designed, we shall then proceed 
to prove that all the parts of a flower are homologous with 
leaves. In doing so, we shall examine the several organs 
of reproduction, both as they exist in a natural condition, and 
in an abnormal state, commencing with the bract, and then 
proceeding in a regular manner with the different whorls 
of the flower, according to their arrangement from without 
inwards. 
In the first place, it is evident that the bract is closely allied 
* to the leaf, from its structure, form, colour, and from the 
ordinary development of one or more buds in its axil. But in 
order to be perfectly convinced of this analogy, let anyone 
examine the Foxglove, the Lilac, or the Peony, and then it 
will be seen that all stages of transition occur between leaves 
and bracts, so that it will be impossible to doubt their being 
homologous parts. 
That the sepals are homologous with leaves is proved, not 
only by their colour and other characters, but also by the fact, 
that many flowers exhibit in a natural condition a gradual 
transition between sepals and bracts, and the latter, as already 
noticed, are readily referable to the leaf as the type. Thus, in 
the Camellia the transition between the sepals and bracts is so 
marked, that it is almost impossible to say where the latter end 
and the former begin. In the Marsh Mallow (fig. 395) and 
Strawberry (fig. 396), again, the five sepals in the flowers of 
the two plants respectively alternate with five bracts; and the 
difficulty of distinguishing them is so great, that some botanists 
call both sets of organs by the name of sepals. In many 
flowers in a natural condition, therefore, there is a striking 
resemblance between sepals and leaves; and this analogy is at 
