268 <“ NATURE OF THE CARPEL. 
the margins of the lamina of the carpellary leaf out of which 
it is formed, and which is turned towards the axis of the plant ; 
and another, which corresponds to the midrib of the lamina, 
is directed towards the floral envelopes or to the circumference 
of the flower; the former is called the ventral suture (fig. 
586, vs), the latter the dorsal, ds. (See also page 300). 
Fie. 585. Fia. 586. 
Fig. 585, Vertical section of the ovary of the Barberry (Berberis vulgaris), 
on the outside of which are seen a stamen dehiscing by two valves anda 
petal. 0. Ovary. ov. Ovules attached to a projection called the placenta, 
p. st. Sessile stigma.m—Fig. 586. Vertical section of the flower of the 
Peony (Peonia). ds. Dorsal suture of the ovary. vs. Ventral suture. 
Nature of the Carpel.—That the ecarpel is analogous to the 
leaf is proved in various ways, some of which will be more 
particularly mentioned hereafter, when treating of the General 
Morphology of the Flower ; we shall here only allude to the 
proofs of its nature which are afforded by the appearance it 
sometimes presents in double or cultivated flowers ; and by tra- 
cing its development. Thus, in a double flower of the Cherry 
the carpels do not present a distinct ovary, style, and stigma, as 
is the normal condition of the solitary carpel in the single flower 
(fig. 590); but they either become flattened into green expan- 
sions, each of which resembles the blade of a leaf (jig. 587), or 
into organs intermediate in their nature between carpels and 
leaves as represented by the figures 588 and 589. Here the 
lower portion (fig. 589, l), representing the blade of the leaf, 
is clearly analogous to the ovary of a complete carpel, and the 
prolonged portion, s, to the style and stigma. The carpel of 
the single-flowering Cherry being thus convertible into a leaf, 
affords at once conclusive evidence of its being an analogous 
structure. a 
A second proof of the nature of the carpels is afforded by 
tracing their development. Thus when first examined they ap- 
pear on the thalamus as little slightly concave bodies of a green 
colour like young leaves (fig. 591, car), in a short time they be- 
come more and more concave (jig. 592), and ultimately the two 
margins of the concavity in each unite (fig. 593), and thus form 
a 
<< 
