Evening star., 1922-09-03
Effects of Colored
Lights on Plants,

IT is recognized nowadays that M
), living organism is responsible in
itself alone for what il is; neither
its form nor it's properties result only
from its own activity. but are ex-
planned by the whole course of cir
cumstances under which it has de-
veloped. In a word, the state of an
organism is the consequence Of rns
conflict or reaction between its own
interior forces and the exterior forces
that continually tend to modify it. It
is at the same time and by its nature
q function of its condition In the
period Immediately preceding the
present and Of the environment in
which its growth takes place.
/ One of the. great aims of biology
is to study this environment in which
life is modelled; to distinguish the
yarious types of activity that COM
pose ii and to note the importance
and proper function of each. Amid
these factors the luminous radiations
must doubtless play IAN important
part and their study. which has not
yet greatly advanced, will one day
furnish Information that will he
profitable not only in theory. but in
practice.
At one station of agricultural clima-
tology there have been carried on in
vestigations of the action of various
kinds of radiation on plants. Every
; year the subjects are varied, and hav-
| ing observed sensitive plants, be-
81
experimenters have now extended
their experiments to oaks. ferns and
| beans in four different houses en-
/ tirely glazed on all sides, one with
| transparent white glass. one with
| red. the third with green, and the
| fourth with blue. The panes are
almost perfectly monochromatic. hav-
ing been carefully examined with the
spectroscope, and as it is impossible
to find violet glass in commerce. the
experimenters have selected blue
as near it as possible. The four
greenhouses are situated side by side
j in identical meteorologic conditions
and are kept automatically at the
! same temperature.
The observations made on oaks and
| ferns confirm. in a general way. the
results already obtained; under the
| influence of red light vegetables grow
with great rapidity; in blue they
scarcely grow at all. Oaks grown in
red light acquire a height four times
as great as those grown in green.
Toward the end of February the
leaves of oaks planted in March of
the preceding year in the white
greenhouse had turned completely
yellow: only a few leaves Of the
trees in the red greenhouse had
turned this color. and those in the
green and blue houses had still a
| foliage Of beautiful green.
On the other hand. the investi-
gators have discovered several in
| teresting facts regarding the move
ment of albumenoids in plants. They
eowed beans in pots, which they left
in the open air until they sprouted.
| after which they distributed them in
! equal numbers among the various
| greenhouses. The same day they dug
up some of the little shoots and
I, analyzed them as follows: Total
nitrogen, As per cent; albumenoid
nitrogen 0.276 per cent. -.
A month afterward they dug up
other shoots. then completely de-
veloped, with the following results:
White. Red. Green. Blue.
Total nitrosen. 511 8.06 g. a. .iti6.s1
Albumenoid 800. 4.53 4.78 Asa 4. rA-A
| These numbers forced them to ,tEs
conclusion that under all the coisrsd
glasses the prportion Of nitrosen rin-
creases more than under the white
! glass, and that thsii ncrease'is greater
when the radiations are mora fitted
| to act on the ch1orophyl function. So :