Evening star., 1939-12-12
Of Stars, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
By Thomas r. Henri.

BY Thomas r. Henry.
The significance of right-sided and
left-sided molecules in the bodies Of
plants and animals is a line Of inves-
tigation now being conducted by plant
psychologists of the Carnegie Institution
of Washington.
Working on the fundamental problem
Of photosynthesis, the synthesis of car
bohydrates by green plants which is the
cornerstone of all life on earth, they
have found remarkable differences In the
basic elements Of the living structure.
Apparently the functioning of the mys-
terious life process depends upon mere
differences in arrangement of atoms
within molecules which specifically are
indistinguishable.
Some Of the findings will form part
Of the annual exhibit of the latest re-
search work of the institution which
will be presented following the annual
meeting of the trustees December IS.
Life has been extremely selective the
work shows. 1t depends not only upon
the proper combination of chemical ele-
ments, but must have exactly the right
form of these elements in exactly the
right place. Life accepts no substitutes.
The primary builders of food materials,
the Carnegie workers point out, are
green plants. The raw materials for
this manufacture are very simple COM
pounds, carbon dioxide and water. 1t is
chiefly from these that the plants COM
pound the complex substances which,
In one form or another, are the basic
food of all living things. The meat
eater, OF course, is only eating plant
materials which have been incorporated
in the body of another animal.
Numerous attempts have been made
to synthesize these materials in the
laboratory. with somewhat paradoxicsl
results because of the extreme selectivity
of the living organism.
1T is a remarkable fact" says the
Carnegie announcement. that many of
these complex carbon compounds syn
theslZed by plants can exist in two
distinct forms, identical in chemical
composition, but differing in the ar
rangement of the atoms or groups of
atoms, within th& molecule. That diff
ferences OF this nature in the internal
arrangement of the molecule can exist
is due to the fact that single carbon
atom combines with maximum of four
other atoms or four groups of atoms.
which are arranged symetrically in space
about the carbon atom. The molecule
thus composed can exist in two dis
tinct forms, depending on the arrange
ment of the four different atoms, or
groups OF atoms, about the central car
bon atom. These two forms are known
as space isomers. They differ from
each other very much as the right hand
diners from the left, or as an object
differs from its mirror image. The diff
ference is one in structure, in internal
architecture. Each of the two structures
Is asymetrical. They are related to
each other as our two hands, and can
not De superlmposed upon each other
The difference between the two forms
is not readily detachable and can be es-
tablished only by special means Yet this
difference is very significant One form
may nourish an animal while the other
may be quite useless as food. One form
may be sweet and the other tasteless,
One may have decided odor and the
other be odorless. The physiological
action of the two forms is thus definitely
related to the structure of the molecule
The simplest means of detecting
asymetric molecules is based upon their
property Of turning the plane of polar
lied light. One may have the capacity
OF turning it to the right while the
other will turn it in the same degree to
the left. The raw materials. carbon
dioxlde and water, from which plants
synthesize these complex substances are
completely symetrical 1t is significant
that in the synthesizing process only
one OF the two possible forms of isomers
is formed in the plant but when the
same compound is synthesized in the
test tube equal quantities of the two
lsomers are always produced. The COM
monest Of all carbohydrates is glucose
In nature only one of the two possible
forms of glucose is found.
Another important property of iso-
merlc substances is that the asy1netrv
persists throughout long series of chem
lcal changes. Consequently starting
with asymetrical substances, the products
will also be asymetric wherever this
is structurally possible. Asymetrv be-
gets asymetry. 1t may be that this
fact accounts for the asymetrical nature
OF the substances synthesized by the
plant. Many of the leaf pigments which
play an important part in the process
OF synthesizing hydrocarbons from car
bon dioxide and water are themselves
asymetric. This asymetry apparently is
impaired to the products of the synthe-
sis. AS consequence, where the posi-
bility exists for two isomers to be formed,
usually only one form appears.
I'm like manner this asymetry is passed
on to the other materials which are
formed in the plant, and in turn to the
bodies of animals which live on the
plants, and ultimately to the animals
which live upon these other animals.
So completely adapted are living organ
isms to one of the two possible forms
of chemical compound that they