120 THE OVULE. 
meet and become united; the midrib forming the back or 
outer part of the cell; and the united edges being in, or 
turned towards, the centre of the flower. The ovules are 
developed at the inner part of these edges, one row along 
each margin or edge. This arrangement of the ovules is 
well seen in tulip, iris, lily, hyacinth, in which there are three 
cells in each germen ; and in the pea and common celandine, 
in which there is only one cell in the germen. The cell be- 
ing analagous to a folded leaf, the ovules resemble buds, 
which are found growing at the margins of some leaves, a 
in the Bryophyllum calycinum, and the Malaxis paludosa. — 
462. This view of the origin of the parts of the flower is 
supported by examination of the flower in its earliest stage; by — 
a general resemblance in structure between the leaf and the _ 
calyx and corolla; by the form of the bracts or floral leaves, 
situated betwen the leaves and the flower, and intermediate 
between them in form; by the readiness with which, as in 
double flowers, the stamens and pistils become petals; by 
the resemblance between petals and sepals, which, in many 
cases, are hardly different, as in the lily tube, the tulip, the 
hyacinth, and many other flowers; by the frequency with 
which petals and sepals pass into each other in some plants, 
as the paeony rose, and others of the Ranunculus tribes 
and by the strong analogy between leaves and sepals, the 
latter of which are often found growing into leaves, a5 in 
rose, water avens, &c., the sepals of which are often e 
ed and divided into leadlets, like the regular leaves of the 
_ plant. In Nympheea, the different parts of the flower are 
