Evening star., 1895-09-14

not only admire but
gather the autumn leaves understand how
they are shaded .and tinted in natures
| workshop, which is now open to all?
Ihe Department of Agriculture is solving
this problem, which has always been a
great mystery to botanists, I'D to very
recent years. The writer a few days ago
visited the laboratory of Albert f Woods
of the division of vegetable physiology and
pathology, and learned a greater part of
the results of his studies in this line. Mr..
Woods speciality is the study of all the dis
eases of plant life, and consequently he
has devoted considerable of his attention
to leaves. which are the lungs. or breath
ug organs, of plants. 1t Is now believed
that autumn leaves are diseased. or rather
that they are abnornalities. This is all
new science. 1t is the revelation of the
ing up to date.
How n Lenf Is Constructed.
First. we must definitely understand the
anatomy of the leaf. Here it is in few
words, as described by Mr.. Woods. If you
take large bag and fill it with potatoes
until they lie four or five deep. when the
bag is fattened out you will have a first
| rate model of a leaf on a colossal scale.
dermis, or outer skin, of the leaf The po
tatoes represent the cells, within which the
leaf makes its food This food consists eli
tirely of sugar and starch. Starch is made
by the leaf by chemically combining water,
absorbed up through the roots of the tree,
and caIbonic acid gas, breathed in by the
leaves themselves. Both the water and gas
are absorbed by the protoplasms. or living
substances. in the cells, as Well as the
minute grains OF pigment which furnish
| the color of the leaves. Under the influence
of sunlight certain chemical changes take
place i'll the carbonic acid gas and water.
and their elements again coming together
form sugar. The sugar is transferred from
one cell to another in the leaf, gradually
becomes diffused throughout the stem.
reaches the branches, limbs, trunk and
finally the roots of the tree.
Any force which prevents a leaf from full
filling it's functions of making starch will
cause it to change color. These difference es
are caused by changes in the grains of
color pigment Green, which Is character
istic of the greater part of vegetable life, Is
very complex in its composition. 1t is not
produced in plant life except in the pres
ence of sunlight. 1t Is the result of a COM
lima ion of colors. which, when mixed, APP
pea / 8 solid green. Hence leaf colored
o.ner wise than green is not natural.
A Natural Paint BOX. 4
Red is one of the color elements of
leaves. Reddish colors are generally in a
liquid form, in the sap contained by the
leaf cells. Yellow is another principal color
element. This. combined with green. is the
natural shade of the grains of pigment
| within each cell. Brown is the normal
color of the walls of the cell. The cell,
which, in the first Instance we likened to a
potato, for closer details of structure may
better be compared with a small rubber
ball, very thin. filled with the red dye
which dissolves and colors the whole solu-
tion. Also add Paris green, whose minute
grains will not dissolve. Yellow grains of
some powdered substance, likewise insolu-
BILE, should be mingled with the green
| ones. The rubber ball itself is brown, cor
| responding to the color of the cell walls
The combination OF all these co!ors in the
| one ball, when seen in the light, is the
green tiEt of plant life.
When any one of these elementary colors
| just described disappears the general effect
| of the remaining colors clustered in that
particular place is changed. just as would
1 be the case If you had lot of green beads
| mixed with brown ones. yellow ones and
| red ones, and took away any one of these
| shades. If ar autumn leaf turns red. for
| instance. its color is due to the fact that
/ only a red pigment is left If yellow. all
| the otner color is destroyed except the
| minute yellow grains. If it changes to
] brown. that is the sign that the leaf is
| dead. All living. color has disappeared
| leaving only the brown walls of the cells.
| The brown leaf. therefore. may be COM
| pared to ruined castle, deserted of all
4 interior life. and whose hollow walls still
| stand. Or the brown leaf may be said to
| be emblematic of the human skeleton, in
which stElile may we'll be seen The appro-
priateness Of the lines which mention man
kind as green today, tomorrow scar"
Jnck Frost Not AIl to Blame.
Mr.. Woods says that many people other
wise well informed make the mistake of
supposing that the frost alone is the cause
of the variation in the color of autumn
| leaves. The leaves in this season really
Frost, however, hastens the destructive
action already beginning to take place. Any
conditions Of climate which cause the
gradual death of leaves produce q high
variety of colcrs. Hence in long-dra wn-
out autumn, when the days gradually cool
from summer heat to winter snow. are to
be found the most beautiful autumn leaves
whereas in those autumns in which the
frost comes early and the weather is irregu-
| lar fewer are to be found. An early frost
Will cause all leaves to turn to a dead
brown.
Crimson and scarlet autumn leaves-the
most beautiful Of aIl-are more abundant in
| the cooler portions of this country than in
| any other place in the world. Europeans
VINO have coveted the luxury of our au-
tumn foliage have frequently planted cut
| tings from such trees in their native coun-
| tries, but without success. When these
| trees are deprived Of their native soil they
| patrioticaliy refuse to make beautiful the
| landscape of other nations. RotaniStS also
4
| this country are much more productive Of
| beautiful autumn leaves than those of the
west The reason for this is that the soil
| of the east is humid. or damp, whereas
| that Of the west is arid. or dry.
Trees Cast eR Dead Leaves.
| It is interesting to notice how trees
finally cast off their leaves in the late
| fall The falling of leaf Is brought about
| by the formation of a little thin layer of
| vegetable tissue at the point where the
| leaf stem joins the branch of the tree. After
leaf ceases to make starch and sugar for
| the tree this tissue begins to grow. and
actually cuts the leaf off. 1t is therefore
not mere breaking away, on account Of
| the winds bending the dried stems, but an
automatic severing of the member, no
longer useful. After leaf has fallen the
scar left in the end of each twig becomes
entirely healed over. The falling of fruit
| when ripe is dependent upon the same pro-
CESS
Botanists have learned how to make a
tree shed it's leaves artifcally. By making
the surrounding air very dry, so that the
evaporation of moisture from the leaves is
too great, the plant may be made to cut
off leaves in a very short time, even early
| in the spring. On the other nand, il the
soil be made too moist, and the roots be-
come smoti, red or drowned SO that they
cannot absorb moisture, the same falling
will yxhn wis fn hra aH