Indian chieftain. [volume] (Vinita, Indian Territory [Okla.]) 1882-1902, 1882-11-10

have been asked whether the state.
ment now going the rounds OF the pa
pers that "a dead branch on tree
makes almost as great strain on the
main plant for moisture as does living
one" Is accurate or not The statement
Is coupled with another referring 10 its
practical application in tree culture, the
conclusion being that every dead
branch "should be at once cut away"
Briefly 1t might be answered that the
first statement Is true In the main, and
that. without any do ibt at all. the con-
clusion Is a wise one and ought 10 be
followed In practice. To explain this
matter will take considerable more
space. and in order TO understand Il we
must 20 10 vcge elable physiology and in
quire into the nature Of the evaporation
of water from plants. II was long sup.
posed TO lie physiological process, and
was considered 10 be entirely different
from ordinary physical G aporatioE. As
long as this view was held the process
was called Transportation, 10 distinguish
1t from the physical process The
breathing pores. the SONATA. which oc-
cur in the epidelms OF all leaves in
great numbers. were supposed to be
organs of Transportation. which was con-
sidercd 10 be one of the most impo tant
functions of the leaf.
Within few years. however. our
knowledge OF these matters has been
greatly increased and we now know that
the escape of water from the leaf does
not differ In any way from the evapora-
ton of water from any other moist sur
face. A leaf is n mass OF cells. every
one Of which Is gorgcd with watery mat
ter. which in a dry atmosphere, as a
matter of course. tends 10 escape. The
epidermis, composed of dryish, impervi-
Gus cells. which entirely surrounds the
watery cells Of the leaf, would prevent
almost completely the evaporation OF
water from the latter were it not for the
breathing pores before mentioned.
These pores are for permit ng the free
ingrcss and egrcss Of gases, particular
ly oxygen. carboni. acid and probably.
also. ammonia. Now. when the pores
are open for their legitimate purpose il
happens that more or less water cs-
capcs, II the air Is dry. II the air hap
pens to be very moist. the loss OF water
through the breathing pores Is very liz
tie or even none nj all
Wcmay put II In this way: the Leaf
loses water simply because il IS waters
structure: its epidofmis l. designed TO
prevent this loss. and the lretihine
pores with their power Of opening and
closing are for the samc purpose. 4
leaf instead Of being an organ Of evap.
orafion Is actually structure in which
evaporation Is quite su ccssiully
chec ed Careful experiments made
under my supervision in the Iowa Agri-
cultural College in 1SS0 BY Miss ida
Tuifcbell. graduate student. demon
sfratel that the evaporation from q
moist piece cf dead wood was ex city
like that from living leaf Now when
dead branch is large enough to Ieep
continually moist in the interior Il viii
in dry air constantly lose water b. evap-
GRAFTON from its surfsce. This water 20
lost Is taken from the tree. and must
have been supplied directly or Indirect
y BY the living portions. Moreo er. i
must be remembered that q living
brapch Il well protected against loss d
water through evaporation. By the cpl.
dermis which co ers all lie surface wheu
young. or the imper ious cor<y barz
which is always found On Il when older.
Wien = branch dies these protecting
de ices soon fall into decay and the va
ter. 50 carefully guar led BY the living
paris Of the p'anf. Is wasted by e. apo
ratioE-I,et- Bc<sty. IN A. T. 1r7tvos-