The Yale expositor., 1897-07-23
culture.

1t certainly Is required Tor the so-
luton of other food substances,
as well as for maintaining the
proper physical condition OF the
tissues. But there are few per-
sons who have any adequate idea
of the vast amount of water which Is
absorbed by plants from the soil. Even
those whose business Is to teach what
Is called Botany" in the schools rare
ly know what plants do In THIS re-
spect; and the same may be salu Oh
those whose business is to grow plants,
to cultivate them, TO manage SOIL ana
surroundings so as to obtain the best
results for the labor bestowed. The
facts are remarkable, and may wei
astonish all VINO become acquainted
with them. Believing that sucn ac-
quaintance may be valuable 10 some
who may here gain an Introduction
the writer takes pleasure In perform
ing the ceremony. In the hrst place. ~
may be stated that leaves in the orui-
nary health state absorb little or no
water from the air. There has peen
much difference of opinion upon THIS
point, and even scientists nave not
agreed upon il. Gardeners sprinkle
the leafy portions Of plants win
water, and say that the revival which
takes place in whiting leaves proves at
once that the water is absorbed. MOI
unfrequently the statement Is maue
that field plants (such as maize) revive
at night by absorbing through the
leaves and stems the dew which is de-
posted upon them. Certainly wllted
plants do recover their lresh anu
dealthful appearance when copiousiy
showered with water, though not
drop reaches the roots. Certainly
field of corn in q dry time presents
conspicuous enough difference OF ap-
pea-ance in the middle OF a hot AFTER
noon and the early morning after
dewey night. But do these things and
others like them show that leaves abb
serb water? A little attention Will
show that they do not. IL the florist
will take a plant whose leaves have
begun to droop on account OF the want
of water, and will place 1t under
glass vessel, he may soon see that,
without the addition OF water at all,
the leaves become plump and assume
their proper positions, as when copi-
ously sprinkled. What can be the
meaning of this? After little time
water may be observed condensing
upon the inner surfaces of the glass,
in dew-like drops. The air within the
vessel becomes saturated with mois-
ture from some source, while the
dropping leaves are regaining their
turgidity. The fact is, that even from
these wilted leaves, while In the open
air, large quantities of water are es-
Gaping. If by any means this amount
is checked, the continuous supply from
the roots soon fills the leaf-cells and
restores their healthful condition.
When the plant is showered with
water, this IS exactly what takes place.
1t is true, experiments have proved
that leaves may and do absorb water
abundantly, when they are immersed
in the fluid, and II is also probably true
that some water may be absorbed by
wilted leaves fro drops adhering to
their surfaces; but SO far as concerns
the great and useful supply OF water
10 healthy vegetation, We may unhes-
tatingly conclude that leaves have
nothing TO do with its absorption.
None of 1t Genes directly from the air.
Atmospheric dew does not gain en-
trance TO the tissues. The soil fur
ni,hes the water, and the roots take
II up. There is no other source nor
other organs for the work. If the
roots send up as much or more than
the leaves transpire, the latter con-
tinue turgid; II not, they wilt. J.
Burrill.