The record-union., 1897-11-20

bleed when it is cut and the time OF
greatest flow both upward and down.
ward is neither spirng nor fall, but
midsummer. This is true, because then
the top makes the greatest demands
on the roots at that time and the food
is being manufactured in the great
est quantities by the leaves.
Growth in a plant is due to an in
crease in the number of the cells COM
posing it. The method by which it is
accomplished is as follows: The cell
becomes filled with an excess of water
and an abundance of food material,
under which conditions the cell be-
comes active in changing the food ma
terial into cell substance, and because
of the excess of water the cell wall is
stretched and timer The cell wall is
continually being added to by the act
i've cell, and if we'll stretched the MOLE
cule's new material will fit in between
those of the old, and the cell wall will
Increase in size and not in thickness.
When the cell and cell wall have in
creased to a certain point the cell sep
arates itself into two halves, and a
partition of new cell wall is deposited
between and two distinct cells are the
result. 1t will be seen thus that growth
results from the excess of water in
tissue well supplied with food ma
teriaI.
Scale insects feed chiefly on that part
OF the plant through which the sap
must pass, whether it be the water on
the way to the leaves or food material
travelling towards the roots. The
structure of the plant in this region
consists of a layer of living, active
tissue lying outside of the wood tis-
sue, which is composed of cells that
have become thick-walled and then
dled, and forming the supporting It's
sue of the tree. Outside of the living
layer occurs the bark, consisting of
dead and dry thin-walled cells whose
purpose is to furnish a protecting layer
over the living tissue. The living tis-
sue increases, and the older cells next
the wood become thick-walled and die
adding to the wood, and those on the
outside die and dry, adding to the
bark As the cell wall forms a cover
ing to the cell that must be overcome
by internal pressure in order that the
cell may grow, SO the bark offers
resistance to the growth of the tissue
until it is made to yield. The tissue of
which the bark is composed has a GER
tain amount of elasticity, but growth
would not be possible if the bark did
not crack and make way for the sue
ceSSlvely larger layers of newer bark
Under normal conditions the old bark
f1akes off and disappears as it cracks,
and the tree maintains a clean, smooth
condition, but this is only possible when
there is a regular growth, which will
push off the bark at the same rate that
1t Is produced by the death of the outer
cells OF the living layer of the cells be-
meath it.
Scale insects are provided with a. pe-
cuiiar long. slender mouth part that is
worthy little attention IL you exam
Inc young scale before it attaches it.
selfit will be seen to possess a long pro-
hoscis laying along the breast between
the legs, and longer than the body. but
concealed beneath it by being bent lust
beyond the middle so as to bring the
point very nearly in contact with the
base. The method BIZ which this pro-
boscls IS inserted in the hard substance
or the bark has not been described nor
observed, but is very evidently as fol-
lows:
Just back of the mouth there are two
horny processes just in the right position
to grasp the proboscis a short distance
from the end The proboscis is doubt
less held by these processes as the insect
pushes down against the plant and by
taking hold successfully further and
further up the insect is finally able to
clio
depth greater than the length of it's
body through the hard substance of the
bark of the tree. Many scales have the
power throughout their lives to remove
and again insert this sucking tube into
the plant. but in some the insects seem
finally to lose this power as they become
mature.
The injury resulting from the attacks
Of scale insects may be classed into three
categories. First-Dirtying up the tree
by exuding the fluids obtained from the
plant, dropping it over the leaves and
fruit, forming a trap for dirt and a
breeding place for fungi
Second-Extracting the water and
food material which are needful for the
plant and thus preventing the growth
needful to healthy life; and
Third-Disarrangin the proper ball
ance between top and roots by injur-
ing the bark in way to decrease the
ability OF the branches to convey the
W ater and food.
It ma9 be said that the large scales
produce the greater amount of injury
belonging to the first category. These
insects take the fluids of the plants in
great quantity and give out the greater
part in the form of minute drops thrown
out with considerable force so that
everything beneath each insect within a
this sticky, somewhat sweetish fluid
This fluid is often very attractive to
insects and is a very suitable substance
for the germation of the spores of
fungi. Wherever these scales are abun-
dant there is very common black
fungus which we cali the black smut
which crows in great abundance. This
and the dust that is also collected by the
sticky substance forms a dark cloak
over each leaf. The purpose the leaf
chiefly Dlavs in the economy of plants
is to manufacture the starch from which
sugar and fiber of which the plants are
composed. Now this manufacture of
starch goes on only under the influence
Of sun light and whenever a leaf is pro-
tected from the light it becomes no Ion
ger o source Of income. but a source of
expense to the plant.
The seriousness of this kind of injury
viii thus be understood. Besides this
The spot fungi becomes very much more
serious as these fungi only enter the
plant after termination on the surface
of the leaf and as long as the leaf is
dry II Is ifl1nnssil for. than, Ia e.ai, On