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THE LADIES’ MAGAZINE OF GARDENING. 
vigorous, the young plant puts forth buds from its stem, and soon exhibits 
its characteristic form and colour. 
These differences in form and colour, according as plants are grown in 
light or in darkness, were early noticed by Hay, and afterwards by 
M. Bonnet, in his Recherches sur l’Usage des Feuilles, p. 210. In the 
year 1771 9 Dr. Irvine described still more minutely the influence which 
light exerts on vegetation. 44 Plants,” says he, 44 though furnished with 
water, heat, and air, grow imperfectly if placed in a dark box, and never 
contain anything but a watery juice ; hence the rays of light are in some 
way necessary to the perfect growth of vegetables; since, when deprived 
of this influence, they all agree in the nature and qualities of the juices 
they contain; nor have they that variety in colour and flavour which 
they had before. The most pungent vegetables become insipid, the 
highest-scented inodorous, and the most variegated in colour of a uniform 
whiteness, when secluded from light. Yegetables, too, which grow in a 
natural situation, readily burn when dry; but a vegetable reared in a 
dark box contains nothing inflammable.” ( Essays on Chemical Subjects , 
p. 430.) In regard to colour and smell, similar observations were made 
by Professor Robison on Tansy ( Tanacetum vulgare') and other plants, 
which, when grown in darkness, were white, and afforded no aromatic 
smell, but when brought into daylight, the white foliage died down, and 
the stocks then produced the proper plants in their usual dress, and 
having all their distinguishing smells. ( Black's Chemical Lectures , by 
Robison, vol. i. p. 532.) 
The great influence which light thus exerts on the colour and properties 
of plants must be regarded as altogether local in its operation, affecting 
only those parts to which it has free access ; and, accordingly, the green 
colour, and other properties to which light gives rise, may be again ob¬ 
literated by the simple exclusion of that powerful agent. 44 Thus, if a 
portion of a growing fruit,” says M. Senebier, 44 be covered with a piece 
of tinfoil, the uncovered portion may become perfectly red, whilst the 
covered part exhibits only a pale or yellowish hue; or grapes, which would 
have acquired a violet colour under a full exposure to light, take on a 
greyish hue if inclosed in black paper. Those leaves, too, which may 
only partially cover growing fruit, and thereby intercept the sun’s rays, 
delineate, as it were, on the fruit beneath, the limits they set to its action. 
(Mem. Phys. Chimiques , tom. iii. p. 146.) In this manner, apples or 
other fruits may be marked with the impressions of leaves artificially 
glued on them ; and fruits so marked, it is said, are often exposed for sale 
in the bazaars of Persia. In North America, the operation of light in 
colouring the leaves of plants is sometimes exhibited on a great scale, and 
