The Washington times., 1901-09-15
PLANTS NEED SLEEP.
Trees Deprived Of 1t Are Killed by
Insomnia.

| Insomnia.
| Although insomnia is generally attrib-
uted in human beings to some disturbance
| in the brain. 1t may occur. we are told
| where that organ is non-existent. 1t is
| asserted, with some show Of plausibilfty
| that some of the London trees are suffer
ing from that malady. We know. indeed
| that plants experience periods of repose
analogous to the sleep of animals. so 1t
| is possible that, even though nerve CEN
| tres are abse2t, they may be susceptible
of overstimulation, and suffer from its
consequences. Light produces the same ef-
| feet on them as on animals. 1t calls into
action processes such as respiration
Transportation, and assimilation, WITH
growth as the result. These are checked
by darkness. With many plants, as the
light fails, the flowers close, the leaves
tend to fold up, the leaf stalks more OF
less hang down. They are evidently TAX
ing nights rest. Plants. however, there
are which, like certain animals, and even
members of our own species, are noctur-
nal in their habits, while others unblush-
ingly go to bed. that is to say, close their
flowers. in broad daylight. We are not
aware that plants under natural condi-
tions ever suffer from want of sleep, and
undoubtedly they are very successfuf In
accommodating themselves 10 clrcum-
stances One species, for instance, pc
longing to the same genus as the edel-
weiss. may be found growing on an Eng
lish moorland hardly above the sea level,
and on an Alpine slope 5000 feet high.
In the one case, the snow seldom con-
ceals it for more than few days in the
year. in the other 1t Is buried beneath a
thick carpet for perhaps six months On
a mountain in Central Europe species
will "go to sleep every night through
the summer, while in polar regions 1t will
crowd the business of its life into con-
months. and apparently be as vigorous
under the latter as the former condi-
tions. Temperature, in fact, for many
plants seems to be more Important than
the distribution OF light. according to
geologists, there was time when alders,
poplars, lines, planes. and other forest
trees fiourished in Spitzenbergen, not far
short of the eightieth parallel of latitude.
The fora at the present time consists only
of lichens, grasses. and a few herbaceous
plants. Yet there is no reason to suppose
that any material alteration in the earth S
axis of rotation has taken place since that
epoch in the tertiary era. so that the
change of the fora must be dependent on
a change of temperature. But the late Sir
w. Siemens showed that some plants can
quickly modify their habits, for by means
of electricity, he kept up a continuous
light in a greenhouse, aand found that
they bore flowers and fruit in a shorter
time without seeming TO be the worse
ers of accommodations.
1t may be able to carry on work for
long spells, if it is allowed to do the same
Ia regard to sleep; but it may break down
if altogether deprived of repose. This is
said to have happened in the case recent
ly quoted, where powerful arc lights are
accused of causing the leaves to wither,
and drop prematurely from the branches
most exposed to the glare. The theory is
not impossible, but before it is accepted
the statements on which II depends must
be established by careful and prolonged
observation. Trees in streets exist under
very abnormal conditions. They have
bouutiful allowance of dust but no more
rain to wash them than If they grew in
the country. Instead of open ground
around their trunks. giving water an easy
passage to their roots, they are surround
ed-except for foot or two-by imperYi-
GUS tagging and pavement Their envi-
ronment, in fact, is such that one often
wonders how they manage to live at all.
Under such conditions their constitutions
might be affected by the slightest strain.
Experiments should be made on the same
tree to see whether leaves in shadow suf-
fer less than those exposed 10 Continuous
light, and what effect is produced on the
foliage In its earlier stages. AS light Is
stimulating, and as plants under ordinary
circumstances show a tendency to grow
toward it, We might expect the buds thus
exposed to burst and develop more quick
iy than the rest.-London Standard.