Evening star., 1939-01-31
Of Stors, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
BIZ Thomas r. Henry.

By Thomas r. Henry.
A device for measuring concentrations
Of chlorophyl, the green pigment Of
leaves and grass which Is the corner
stone of all life on earth, has been per-
fected by DR.. Earl S. Johnston Of the
division of radiation and organisms Of
the Smithsonian Institution.
The device depends on the use of q
thermocouple, hitherto chiefly known
because of its use by astronomers to
measure minute differences in the radia-
ton of the sun, planets and stars. First
all the chlorophyl is extracted from the
leaves with alcohol. The green pigment
remains in solution In the liquid.
Through the alcohol is passed beam
Of filtered light, all in narrow band Of
wave lengths at the red end of the spec
trum which is absorbed by the chloro-
phyl molecule. The more of the pigment
in the solution the less light will get
through.
The radiation which does escape alb
sorption falls on thermocouple In
which two elements with different heat
ing capacities are joined together. The
result is to set up minute electric cur
rent which varies very precisely with
the amount Of radiant energy which
gives rise to it. This current is recorded
with a galvanomometer and constitutes
an incredibly delicate and accurate
measure OF the chlorophyl concentration.
The chlorophyl in plant leaves is the
great catalyst of nature, by means of
which carbon dioxide from the air and
water taken up by the roots are trans
formed, through the energy Of sunlight,
into plant carbohydrates which consti-
tute, in turn, the sugars and Starches
which are the fuel of animal life. In
studying this basic photochemical mech
anism 1t is essential that plant physiolo-
gists know with great precision the
amount of the green pigment which
takes part in the reaction.
There are two kinds Of chlorophyl, A
and B, which absorb slightly different
wave lengths of light. Thus far, DR..
Johnston says, it has not been possible
to make independent measurements OF
each variety, but this may become feas-
ible through development of the new
method. With more accurate knowledge
of chlorophyl concentrations 1t will be
possible to measure more precisely the
amounts OF solar energy which enter
into the photosynthetic process, and also
the reactions of the other elements.
The Ancient and Honorable Associa-
ton of Tellers of Big Fish Stories at its
annual convention here the other day
passed unanimously a resolution calling
for the elimination of DR.. Leonard P.
Schultz, the Smithsonian Institutions
curator of fishes.
DR.. Schultz has just reported a way to
weigh big fish, and especially whale,
just by looking at 1t and doing little
mathematical calculation. 1t consists
OF a mathematical formula which ex-
presses the relationship between the
length and weight of marine animal.
Essentially all that is necessary is to
get within sighting distance OF the crea-
ture. Then an accurate measurement of
its weight can be determined much as an
astronomer can determine the compare
tive weight Of a distant star by obser-
vations from the earth.
There is fairly constant relationship,
he finds, between length and weight.
This has been found to hold for all
whales or for all large fish of the
'streamliped" varieties on whom both
weight and length measurements have
been taken. The weight, he finds, equals
constant multiplied by the length
raised to certain power-the power
and the constant varying somewhat for
each species.
Henceforth tellers Of fish stories will
be obliged to do some quick thinking
to get their weights and lengths to
check. This, they hold, will be an in
tolerable rein on the free flow of the
imagination when they gather around an
open fire after cold days fishing.
Otherwise the formula is expected to
prove of considerable advantage in
scientific Investigations. The length of
whale or shark can be estimated fairly
accurately from a naked eye or field
glass observation. Then the weight can
be calculated and it may be possible to
obtain valuable data on the growth rates
Of these animals.
Similar formulas have been proposed
In the past, DR.. Schultz says, but none
OF them have given convincing results.
Among whales as among men, he
stresses, there are bound to be individual
differences and some will depart more
radically than others from the theo-
retical weight-length relationship. He is
convinced, however, that the formula
will hold for these big sea creatures on
the average as well as similar formula
holds for human beings, among whom
weight and height is q well-recognized
relationship.