1878.] 
What is a Flower t 
never attain to any development beyond the embryonic 
cellular tissue ; ferns which develop early forms of vascular 
tissue ; Conifers reaching the higher stage of wood-forma- 
tion ; oaks and alders, poplars and willows attaining to the 
leaf stage; — and beyond these, what? The true dower- 
bearers, the dichlamydeous phanerogams, whose life-wave — 
passing through all the earlier stages of cell, wood, and 
leaf — attains to the development of corolla, and floods the 
world with a glory of colour previously unknown. 
3. The corolla of nearly all flowers, when first formed in 
the bud, is of a pale greenish tint. The cells are filled with 
protoplasm, partly fluid, and partly granular in the form of 
chlorophyll. As the bud swells, the cells of the corolla are 
rapidly enlarged, at the expense of their contained proto- 
plasm. If the protoplasm is entirely exhausted in this 
process, the cells, when the flower opens, are empty or 
filled with a thin transparent fluid, and the corolla is white, 
from the total reflection and transmission of all the light 
which falls upon it, the intensity of the whiteness depending 
upon the smallness of the cells. If there is still protoplasm 
to spare when the corolla cells are developed, this surplus 
is differentiated into substances either fluid or granular, 
which give colour to the cells they occupy. In proportion 
to the quantity of this surplus will be the quantity and 
intensity of the colour. 
Colour is of course produced by the absorption of certain 
constituent rays in the white sunlight, and the reflection of 
the remainder. The colours of flowers are nearly all 
secondary colours, combinations of two out of the three 
primaries, red, green, and violet. It is evident, therefore, 
that the colouring-matter in the cells is monochromatic — - 
that it absorbs only one of the three primary colours, or at 
least that it absorbs one in much greater proportion than 
any other ; and since the colours of flowers are mostly very 
bright, the quantity of any other colour absorbed must be 
small. The brightness of colour is in proportion to the 
absolute amount of light reflected to the eye. White light, 
which is a ternary compound, will always be brighter than 
any combination of portions of its constituents. 
The secondary colours are brighter than the primaries, 
because they are composed of the combined light of two 
constituents instead of the single light of one. 
Grey is a feeble white— a mixture of the three pri- 
maries, but not in quantities sufficient to give the effeCt of 
white. 
Brown is a feeble yellow— a mixture of red and green in 
