‘THE FLOWER. | 139 
Just as the calyx may be monosepalous, or polysepalous, so the 
corolla is monopetalous or polypetalous. The flower of the 
Fig. 173.—Flower of Geranium. Fig. 174.—F1 f Gillifl 
Geranium (Fig. 173), and of the Rose, and Pink, have their petals 
perfectly distinct, so that one can be detached without inter- 
fering with the others. On the contrary, the Lilac “ 
(Fig. 175), the Primrose, and the Belladonna, have \ 
their petals united together at their edges, so that 
one cannot pull off a petal without breaking in on 
an adjacent one. 
When a flower begins to expand, the petals are 
always free. The transformation of a corolla, at 
first monopetalous, into a polypetalous corolla, takes ,. 115 sronopela- 
place in the bud, just as we have already shown to !uscoroliaof Lilac. 
be the case with the calyx ; that is, the free extremities of the petals 
are supported and united in one whole by a common and con- 
tinuous membrane. 
We have remarked, that the sepals are developed on the recep- 
tacle in succession, whilst the petals appear, on the contrary, 
simultaneously. This fact may help us to resolve a problem, 
which much occupied the attention of the older botanists. 
In the Lily (Fig. 176), for instance, the floral envelopes are 
composed. of six divisions, which are white, and of a delicate tissue, 
analogous to petals. Do the whole of these divisions constitute a - 
corolla? By no means. Without mentioning the differences of 
shape, size, structure, and position, which could not escape the 
eyes of an attentive observer, we can show that the pieces of the 
external whorl of the Lily are developed in succession, like sepals, 
