pudica, and Mimosa sensitiva. For an exposition of the causes, and 
accompanying circumstances of the waking and sleeping of animals, 
see Virey, Philosophie de l’Histoire Naturelle, p- 3165. 
This species, like all the others, contains oxalic acid in the state of 
a binoxalate of potass, which makes the leaves a grateful refreshing 
vegetable, in the warmer climates of the world; but the excessive use 
of which, for any considerable time, produces serious ill effects. It 
has been supposed that the gradual formation of vegetable acids and 
alkalis in plants, is the cause of that change of colour which certain 
parts are observed to undergo. Thus the corollas of Echium vulgare 
and Symphytum officinale are red in the bud, but become blue after- 
wards ; that of Myosotis versicolor is first yellow, then blue. A pleasing 
experiment may be performed by placing a bunch of flowers under a 
a glass jar and burning a match among them, when the sulphuric acid 
evolved, immediately alters their colours. So also any infusion of ve~ 
getable blue, as that obtained by soaking the corolla of the Violet, 
Cornflower, Iris, &c. turns red by the application of an acid, and green 
by an alkali, (see Maund’s Botanic Garden, p. 146.) Hence it has 
been supposed, that the gradual change which takes place in the co- 
lour of the leaf in autumn may be accounted for ona similar principle. 
Another hypothesis supposes the minute globular particles, (or globu- 
line) contained in the cellular tissue to assume different tints of 
colour, according as it is united with different proportions of oxygen; 
somewhat in the way that the differently coloured oxides of iron are 
formed. It has been observed also, that the plant retains a larger 
portion of the oxygen inhaled by the leaf, as the season adyances; 
and a change of hue ensues. We are thus deprived slowly of the 
yerdure of spring and summer, while the variety of hues, which form 
the intermediate stages before the woods become universally 
——— russet clad, 
. The livery of the adie year,” 
are as pleasing to the eye of the painter or the poet, as the tender 
green of spring, or rich effulgence of summer; furnishing many a 
touching memento of our own transitory state, thus yielding illustra- 
tions alike to the moralist and divine, when pointing our regards to 
another world, “the fashion of which fadeth not away.’ 
“ A deep and crimson streak 
“ ’*Mid ruin, blooms the rose, 
