CHAP. XIV. 
COLOUR AND SMELL. 
361 
considered that some apparent exceptions to the cases just 
quoted in reality confirm the rule: as for instance, in the 
Campanula aurea, whose flowers are deep yellow, in a series 
otherwise cyanic : it is now known that this plant constitutes 
in reality a genus essentially different from Campanula, and 
called Musschia; and so with others. 
" It will have been remarked that white is omitted from 
these two series. It may be doubted, indeed, whether it 
really exists in a state of purity in flowers, and it seems to be 
rather some other colour reduced to an exceedingly light tint. 
Redoute, the French flower-painter, is said to have availed 
himself with great advantage of this fact. He always placed 
the flower he wished to represent before a sheet of paper like 
that on which he had made his drawing, and he uniformly 
found that the flower would differ from the paper in being 
more yellow, or more pink, or more blue, or in some other 
way. White Campanulas become blue when they are dried ; 
infusions of white flowers in alcohol have always a perceptible 
tinge. Flowers which are white verging upon yellow, yield 
infusions which alkalies bring to a more decided yellow or a 
more positive brown ; infusions of those which are white, tend- 
ing to blue or red, become light-red by the action of acids, 
and greenish by the action of alkalies. 
" It is probable that whiteness, or that kind of paleness 
which constitutes white, is owing to the chromule not being 
completely elaborated. This may be inferred, — 1 . from the 
analogy between this colour and blanched plants ; 2. from the 
much great 3r number of white flowers in northern than in 
equatorial regions; and 3. from a considerable number of 
flowers which are born white acquiring some other colour be- 
fore they die, if exposed to solar light. Thus the Cheiranthus 
chamaeleo has a flower at first of a whitish colour, which 
afterwards becomes lemon-yellow, then red, slightly violet. 
Stylidium fruticosum has its young petals pale yellow, its old 
ones white tinged with red. The flowers of CEnothera tetrap- 
tera are at first whitish, afterwards pink, and finally red. The 
petals of the common tamarind are said to be white the first 
day, and yellow the second. The corolla of Cobaea scandens 
is greenish-white the first day, and violet the next. Finally, 
