The Scranton tribune. [volume] (Scranton, Pa.) 1891-1910, 1897-03-20


into the work of elongating It's stem, II
haply it may bring its leaves to the
light.
,BRAINY ROOTS.
Roots show remarkable intelligence
in the way in which they move through
the ground. 1t is necessary for the pro-
per performance of its duties that the
root be supplied with oxygen. 1t has
no difficulty in obtaining this oxygen
from a. healthy soil. In the tropical
mangrove swamps the soil consists of u
mass of decayed vegetation, where very
little oxygen is found among the putre-
flying substance. The mangroVe ac-
cordngly adapts itself to circumstances.
Its roots begin by growing horizontally
in the normal way. but if not aerated
they proceed to take a turn upward,
grow along in the air for a short dis
tance above the ground, and then go
down again. A root may repeat this
process at intervals. In the aerial parts
is found permeable tissue which al
lows of the free circulation of air be-
tween the cells.
The entire behavior of roots is influ-
enced by gravitation. If the influence
of gravity in a particular direction be
done away with, as by causing grow
gravitation stimulus in all directions by
turns the root will grow quite horizon
tally, thus showing that the downward
direction is due to gravity. The tap
root is stimulated by gravitation in
such q way that it grows vertically
downward, while lateral roots under
the action of the same stimulus grow in
very much more obllque direction. If
now the plant be tilted, the growing
end of the tap root turns vertically
downward, while the lateral roots curve
in such a manner as to restore what
may be called their normal direction. If
by any miSchance the tap root gets
broken off or destroyed, the want is
supplied by neighboring lateral roots,
which now behave toward gravitation
as did the tap root, and change their
sloping direction for the vertical. An
other instance of gravity causing Il
member to grow in a definite direction.
making an angle with the vertical, is
afforded by the daffodi. The daffodil
always hangs its head This depends
not on the weight of the flower, but on
the stimulus of gravity. for no matter
how the stalk may be placed the flower
always makes an angle with reference
| to the direction of gravitation.
When part of a plant responds to
| an external stimulus the whole plant
need not necessarily know in which
direction the stimulus tends. In the
| case of roots a certain part is increas-
| ing in length, and this is the portion
| in which curvature takes place under
| the action of the stimulus of gravita-
ton But this is not the part which
| knows which way gravity is pulling
| Near the tip of the root just behind
| the rOotcap, is a very small patch of
| tissue which perceives the stimulus.
| Cut off the tip Of the root and with
| it this little patch of irritable tissues,
and invert the plant, and the root,
which is thus placed uppermost, grows
vertically into the air. A very inter-
esting experiment in illustration of this
| fact, and one easily tried is as follows:
| Take a thin glass tube shaped like a
boot, the toe being rather short, and
| more than two millimetres long. AL
| low the root of a seeding to grow into
| TINS, liking the plant at the open end
Of the tube. The root grows vertically
| down the tube, and when it reaches the
toe 1t turns horizontally along it. The
tissue al the tip of the root sends a
message up the plant that there is
something preventing it from respond
ing to the stimulus of gravity and
growing vertically downward, and this
is necessitating its horizontal growth
In response to this message the elon-
gazing portion curves at right angles
IN the hope OF thus getting the tip Ct
the root round the opposing structure
But 1t is unconscious that a trick Is
being played upon it, that the root is
fXed in the glass tube unable to move
forward, and that the curvature IN
stead of pushing the root horizontally
forward, acts upon the shoot, pushing
this horizontally in the opposite direc.
tion.
BRIGHT BERRIES.
The berries Of some foreign species
of mistletoe show a remarkable be.
havor in their endeavors to penetra t
the trunk of a tree. The sticky berry
fastens itself to n branch and sends
out root, which, curving over, meet!
the branch again and forms a saddle
like mass of tissues. 1t attempts a
this point to pierce the bark. If un
able to do so the berry is deposited
little further on. The saddle now be
comes detached, and, by another bend
ing of the root is placed once more oi
, the branch beyond the berry. If root
can penetrate in the new station al
goes well, but if not the plant perform
another somersault. one berry tha
was made the object of continued oh
servation performed five jumps In tw
nights and three days. A number o
unfortunate berries We're once seel
hopelessly travelling along the tele
! graph wires in Ceylon, vainly endeav
oring to find a profitable resting place
The sensitive plant and the Venus H.
trap furnish two examples amon
many others of restessly irlitahl
plants which react violently to tn
!, stimulus of contact 1t is a curiou
: and but little known fact that tn
Venus fly trap only responds to n
stimulus when one of the hairs on tn
o centre of the trap" is touched twice
No effect is observed after the hrs
, touch.
The wonderful purposefulness q
, these habits and mechanisms foreve
= dispel the idea that botany treats :
d inert, objectless plants. 1t is instea
- a science of life and living things, ca"
n one of which is endowed with marvel
[ lous and different powers of making tn
V best of life in the sphere in which
/, finds itself.