The weekly herald. [volume] (Cleveland, Tenn.) 1876-1888, 1877-05-31
Spontaneous Motion In Plants.

If children, monkeys and OppOssums
climb trees and suspend themselves In
the air from limbs in various ways, so
do climbing plants. The curious and
interesting movements of this class Of
plants have been investigated by Palm
Mohl, DR.. Gray, Darwin and others. 1t
is well known that the hop, honeysuc-
kle, convolvulus, ETC., always twine
around the stem that supports them in
one direction; that is always from right
to left or from left to right; but few
have attempted to observe by what pro-
cess the ends Of the growing shot con-
trive TO change from one side to the
other Of the central support. If the ex-
tremity of living climber, say of con-
volvulus, growing perfectly free and in
a normal position, be observed, 1t is
seen to hang over from its support in a
horizontal position, and this horizontal
position, if observed from hour to hour,
is seen TO point to different directions.
The end of the growing shoot revolves
in large circle round the support,
always with the same species in the
same direction, either with or against
the sun.
In warm weather this large circle OF
the terminal bud in the air is made In
much less time than in cool weather.
The rate of the revolution varies in diff
ferent plants, and with the same plant
at different periods of its growth. With
the hop Darwin found the revolution to
vary from two and half hours to nine
hours. The apparent object of climb
ing plants is to obtain more light, and
place where leaf and fruit may develop
in the presence of free circulation Of
air, numerous leaves imbibing much
nutriment from the atmosphere. When
hop or Lima bean has climbed to the
top OF its pole, and has half yard of
stem over, by what vital physical force
does it make this curious circle of about
a yard in diameter eighteen inches
from the top of the pole each way) in
search of some new support? If the
bean had instinct or reason could It do
more to find what it most needed2 The
late eminent Psychologist, Mohl, sup
posed this phenomenon was caused by a
dull irritability in the stem, exciting
movement in one direction till circle
in the air was formed.
Darwin tested this theory experiment
tally, but found no such irritability.
Our limited space does not permit us to
follow the experiments of this natural
ist. He found that when climbing
plant first springs from the ground, the
extremity of the shoot performs slow
gyrations in the air, as if it were search
ing a support. By what force do the
roots ofplants search for water and other
aliment, and their moving stems above
ground hunt for stakes and trees to up
hold them in rich currents of atmosphe-
ric food?
The spontaneous movement of ten
drills in the grape vine, passion flower
and Virginia creeper are, if possible,
still more surprising. Touch the ten
drill and you may develop at once its
curling movement. In q few hours it
uncurls itself as if the hint and effort to
catch support were a mistake. Far
mers should know that living growing
plants, not less than all animals, man
included, make mistakes. We live in a
world of mistakes.
A tendril rarely twines itself round
another tendril, although nothing Is
more convenient or more In its way.
What is the full meaning of this power
of selecting and discrimination
Our cultivated plants and fruits not
only select their daily food in the soil
and in the atmosphere, but select in
some degree their associates. Plants,
as general truth, but with many ex-
ceptiOns, are social beings.-E1.