354 
CHAPTER XIV. 
OF COLOUR AND SMELL. 
The following abstract of the views of De Candolle and him- 
self upon this most obscure subject, has been given by the 
author of the article Botany, in the Library of Useful Know- 
ledge. 
" There certainly is no point of either animal or vegetable 
physiology now remaining to be explained, of which so 
little is really known as the cause of the various and varying 
colours with which organic matter is adorned. We see in 
birds the plumage marked with the strongest contrasts of the 
most dissimilar colours, reproduced with an exactness which 
is most wonderful ; we find the breeders of curious races able 
to preserve peculiar kinds of marking, and even to improve 
them, with the most admirable precision ; we also know that 
in plants, without any visible constitutional change, without 
accident, and without any known predisposing cause, a yellow 
flower will become pink, and a pink one yellow ; and we 
know^ that if the portion of the stem thus altered be increased 
by the division of itself, the change is fixed and may be mul- 
tiplied for ever. A dingy brownish purple tulip w^ill suddenly, 
and without warning, burst forth in the most radiant beauty, 
its dull disagreeable colours dispersed, a pure and spotless 
white taking its place in part, and the brightest and deepest 
streaks of crimson adding richness to its purity. If we look 
minutely to these circumstances, we shall find that each par- 
ticular cell has its own colour, — that there is no intermixture 
of tints, but that whatever the hues may be, each has its own 
cluster of cells to represent it : and even in the midst of a 
large mass of uniform colouring, a few cells, or even a single 
one, will secrete a colouring matter which forms the strongest 
contrast with what surrounds it; as in the blood-red orange, 
