136 * THE VEGETABLE WORLD. 
spirally, that is, at different heights, so that the line uniting their’ 
bases is a spiral. 
Sepals are, in short, either alike in size, inserted at the same 
height or distance, free or united, or else they do not show a 
perfect agreement in these points, and thus determine whether 
the calyx be regular or irregular. That of the 
Money-wort (Fig. 164) is regular, and that of 
the Aconite (Fig. 165) is irregular. 
In the Poppy, the calyx falls before the 
a flower blows, in the Ranunculus it is not de- 
Fig. 164.—Regular calyx of tached until after the fecundation of the flower. 
rae i In the Physalis it remains round the fruit, 
very much enlarges, and becomes of a yellow or reddish colour. 
This last phenomenon of colouration brings us to a reflection 
which has its interest. In some cases 
_ appearance of a corolla. The calyx of 
the Pomegranate and that of the Fuchsia 
Fig. 165.—Irregular calyx of Aconite. are red, that of the Larkspur and of the 
Aconite are blue. The calyx may thus be coloured even when 
the corolla is wanting. 
THE Corona. 
All that we have said about the charming sweetnessof flowers 
applies particularly to the corolla, for on that organ nature lavishes 
her brightest colours. In spite, however, of the beauty and 
elegance of shape which we admire in it, the corolla is only the 
immediate envelope of more important organs, which with the help 
of the calyx, it protects against the action of external causes. 
When the fundamental phenomenon of fecundation is effected : 
when the fertilised ovary begins to enlarge, and can of itself 
oppose a sufficient resistance; then nature, which suffers nothing 
useless to exist, throws away this graceful decoration : the corolla 
fades, withers, and falls. If it remains occasionally a short time 
after fecundation, it is probably only to reflect the rays of external 
it 
