Savannah morning news. [volume] (Savannah) 1868-1887, 1886-08-23
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That the amount oflight 10 which living
organisms are exposed exercises a pow
eriul influence upon their development
and growth Is matter of comm0I eX-
perlence. We are most familiar with
the effects or comparative darkness upon
certain plants--as in the blanching OF
celery, asparagus, and lettuce by this
means. or the long white sprouts from
potatoes kept in dark and warm, place
and the cause of this is TO some extent
known. The building Of tissues from
materials taken from without is in most
plants effected by peculiar colured It's.
sue known Ms chiorophyll, and this tissue
can OILY do it's work when exposed to
light. The material out of which the
stem OF the tree OF The seed of the plant IL
formed is first compounded by the
chlorophyll in the leaves. which latter
organs, at the end Of q bright day In tue
late spring or early summer, contain a
large amount Of suem ma eral. During
the night this disappears, being carried
by the sap circulation 10 the place where
1t ID needed for construction. The leaves
are, as it were, the brickmakers for
ali the building going on in the tree.
Through what special channels toe in
fuenee OF light Is exered on the animal
organism, and especially ON man, is not so
clear, but 1t must be effected through the
shin and eye, and through these it proba-
bly, acts on the nervous system, and thus
On the biood-maklng part OF our machin.
cry.
At all events, men living in dark habita.
uons-and especially if this life be con-
tlnuous, as was the case in ancient
prison cells, etc.-become blanched: the
blood does not contain It's due proportion
OF red cJrpuscIes, and such men are sand
to be an1rnic. the observations oil SAM
tary Inspectors and the results OF CON-
pairing death rates of different localities
have, wethin the last fifiy years, fairly
demonstrated that dark habitations are
unhealthy, that Inursaiityis greatest
ia those paTbgOfa clCy wkere the IN 0sses
are most oeAsely paGkeds where theT Stbs-
dOws ,aeeAbuta few feet from a wall. and
whegS IN ths lower stores especially,
direct sunlight cap.seld9m or never, = Ter.
In streets running e9st and West. ii mas
been a4Qlld 3 the people in houses on
the perth OF toe street, living oiiefy
in r9QmSf bayin2 4 southern exposure
with II enty Of sunlight, are heal thierapG
have ~ lower de3thfy 10 than those Lying
on t9e,9pposite SIDE eof the street In aps al.
most Berpelual shadpw.5 ma sa6ts ~ a.
lthss, 9RweyeT, been Very lincertain, as
to whsLnar7 these differences !, We're, not,
largely soE mainly due IN many cases 10
other causes, ~ want OF fresh air.,
poverty, ete, and also- as to sWbether tEa
eanitayyc effects Of light are due to its
stimulating 2nd sinyigOratlnge inf uepce
on the h4lInsn body,lor 70 its II some way,
preventing tpeo dsvel opmsnt TOT causes Ok
disease external 10 The Body. e.~ 80
The recent advances In our knowledge
OF the causation OF certain diseases by
minute vegetable organisms, and OF the
influence OF light on the growth and de-
Ve!0pment OF these organisms, make 1t
probable that II is through this latter
channel that light is especially important
as sanitary agent. The movements Of
many OF the bacteria are strongly in
fiuenced by the amount and direction OF
the light 10 which they are exposed. and
there 10 one bacterlum the movements of
WHICH appear 10 depend entirely on the
influence of light, and which has there
fore been named bdctertUDl phOtODsetricuD
Every change of the color or OF the In
tenstty OF tue light 10 which it Is exposed
induces movements In this organism.
In general, 1t may be said that light
and especially bright light, binders or
stops the development OF the bacteria.
This action Is exerted on the organisms
themselves, and not on the nutritive mat
erial in which they flourish; that is TO say,
II steriized flask OF culture fluid be ex-
posed to the rays OF the sun TOR several
days, and then is inOculated with germs
and placed in the dark, the germs -four
ish vigorously; while II similar flask is
kept for some time In the dark, and then
is inoculated and placed in the sunlight,
the development OF the germs will be
greatly retarded.
Recent experiments made by MIR. Arl-
wing Indicate that In cultures ofthe bQctL-
tuS dnthTdcts, which is now positively
known TO be the efficient cause OF splenic
fever and malignant pustule, the rays OF
the summer sun rapidly stop the germina-
ton OF the spores and hinder the growth
OF the threads, diminishing, also, their In
fective power. TO use the technical
term, they "attenuate the virus" The
Light OF ordinary illuminating gas APP
pears 10 check the growth Of the bacillus
slightly, but its effects are very small as
compared with those OF sunlight.
The practical bearing OF these results IL
evident, and II similar effects are found TO
follow from the exposure to light Of other
micro-organisms which cause disease
such, for instance, as the bacillus OF
tubercle, or the micrococcus OF erysipelas
we have made long step toward the
obtaining Of Scientific basis for pre-
ventive work, and IL may BIO also for
treatment. IL ie not necessary, however,
TO wait for further experiments TO prove
that plenty OF sunshine Is good thing
for all OF us, and we are now In the season
when It is easiest 20 take advantage OF
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