194 
OF FLAN'I s. 
stronger is at hand. There are, however, a few observa¬ 
tions upon the vegetable kingdom, which lie so directly in 
our way, that it would be improper to pass by them with- 
out notice. 
The one great intention of nature in the structure of 
plants, seems to be the perfecting of the seed; and, what 
is part of the same intention, the preserving of it until it 
be perfected. This.intention shows itself, in the first place, 
by the care which appears to be taken, to protect and ripen, 
by every advantage which can be given to them of situa¬ 
tion in the plant, those parts which most immediately con¬ 
tribute to fructification, viz. the anther re, the stamina, and 
the stigmata. These parts are usually lodged in the cen¬ 
tre, the recesses, or the labyrinths of the flower; during 
their tender and immature state, are shut up in the stalk, 
or sheltered in the bud: as soon as they have acquired 
firmness of texture sufficient to bear exposure, and are 
ready to perform the important office which is assigned to 
them, they are disclosed to the light and air, by the burst¬ 
ing of the stem, or the expansion of the petals; after which, 
they have, in many cases, by the very form of the flower 
during its blow, the light and warmth reflected upon them 
from the concave side of the cup. What is called also the 
sleep * of plants, is the leaves or petals disposing themselves 
* “ The periodical change in the direction of leaves, which has been 
called the ‘ Sleep of Plants,’ is undeniably connected with the stimulating 
operation of light. It is established, that during the clear light of the 
sun, the leaves become erect, and move their upper surface to the light, 
whilst, on the contrary, during the absence of light, they either hang 
downwards, and turn to the horizon, or they take an upright position, so 
that the under surface of the leaves is turned more outward. On account 
of this particular position of what has been called ‘ Sleeping Plants,’ we 
cannot properly ascribe this direction to sleep, because the leaves do 
sometimes even raise themselves during this state with greater energy, 
and press upon the stern or leaf-stalk, for the purpose of turning their 
lower surface outwards. This change is much rather, therefore, the con¬ 
sequence of the contest between the activity of the plant, and the great 
activity of nature. This change is the more evident, and the sleep of 
leaves the more striking, the finer and more compounded the organiza 
tion of the leaves are. VVe hence most, frequently observe it in the pin¬ 
nated leaves of leguminous plants, although also in some others, as in 
atriplex. 
That an internal and self-dependent activity is to be taken into ac¬ 
count in this sleep of plants, is plain from the fact that this sleep does 
not equally follow from a short withdrawing of the light, but only from 
its complete and long-continued removal; as also from this other cir¬ 
cumstance, that leaves fall asleep or awake at fixed hours, whether 
the sky be serene or troubled, exactly as happens with regard to ani¬ 
mals. Other stimula, too, and especially heat, have a great influence 
