534 
MORPHOLOGY. 
BOOK VI. 
axis, as in Galium. Now a whorl of this nature is exactly of 
the nature of a calyx, only it surrounds the axis 'of the plant, 
instead of terminating it. As we know that such approxi- 
mations often taken place in the stem in the direct line of 
growth, when the propulsion of the matter of vegetation 
exists in its greatest activity, there is no difficulty in compre- 
hending the possibility of such an approximation constantly 
existing at the end of the system of growth, where the propul- 
sion of the matter of vegetation ceases. But the calyx and 
more inner whorls of the fructification do not always retain 
their verticillate position ; on the contrary, they occasionally 
separate from each other, and assume the same position with 
regard to the axis of vegetation as is naturally proper to the 
leaves. This is particularly striking in a very common per- 
manent monster of Lilium album, known in the gardens by 
the name of the double white lily. In this plant the whole 
verti dilation of the parts of fructification is destroyed; the 
axis is not stopped by a pistil, but is elongated into a stem, 
around which the white leaves of the calyx are alternately 
imbricated ; and in double tulips the outer whorl, represent- 
ing the calyx, frequently loses its verticillate arrangement, 
and becomes imbricated like leaves of a stem. The same 
structure also occurs in the double white Fritillaria meleagris. 
Hence it cannot be doubted that the calyx consists of leaves 
in a particular state. 
The corolla forms the second line or whorl of the fructi- 
fication. It consists of several divisions, usually not green, 
and always alternate with those of the calyx. It is a series 
of leaves arising within those of the calyx, from which it is 
sometimes, indeed, very easy to distinguish it; but from which 
it is so often impossible to discriminate it, that the difference 
between the calyx and corolla has been one of the most de- 
batable subjects in botany. No limits can be found in Caly- 
canthus; the same is true of Illicium, and several similar 
plants. In all Liliaceae, Asphodel eae, Orchideae, and Scita- 
mineae, the only distinction that can be drawn between the 
calyx and corolla is, that the one is inserted within the other ; 
they are alike in figure, colour, texture, odour, and function. 
Whatever, therefore, has been proved to be true of the calyx 
