Evening star., 1939-04-25
Of Stars, Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
By Thomas r. Henry.

A new concept of the mechanism Of
the elemental properties of life, inde-
pendent movement and reproduction,
was presented to the National Academy
of Sciences, meeting here today.
DR.. Warren H. Lewis of the Carnegie
Institution of Washington pictured
hitherto unsupported forces operating
like rubber bands around and within
the single CELL which is the basic living
thing out of which all higher organisms
are built.
These forces, inherent in the complex
chemical stuff life is made of, are purely
mechanistic trimmings and chickering's
of protoplasm which eventually, it may
be. develop into nerves and muscles.
Yet they mark a transition to the
living from the non-living
DR.. Lewis is one Of the worlds fore
most authorities on the behavior of
single cells. His moving pictures of
them, seemingly at work and play, have
been shown to learned societies all over
the United States.
Seen in DR.. Lewis high-power micro
like COWS in pasture.
They move by expanding and con-
tracing They thrust out arms to seize
food. They reproduce by rolling into
balls and splitting in two. This is the
case whether they are normally in
dividual animals like protozoa, or hu-
man cancer cells of whose ways of
life DR.. Lewis has made speciality.
1t looks as if the one-celled organisms
were intelligent creatures
But 1t can all be explained on purely
mechanistic basis. the Carnegie Insti-
tuition biologist told the National Acad-
emy. This requires the assumption
that each cell is inclosed in thin
envelope of protoplasm in the 'gel''
state which is more jellifled in some
places than in others.
Protoplasm is a colloid, like the white
of an egg or like gelatin. Collolds have
the faculty of thinning and thickening
in response to various chemical proc
esses. In a semi-liquid condition they
are known as "sols" When they thicken
they are known as gels"
Experiments with simpler colloid sub
stances than protoplasm, DR.. Lewis said,
show that when the gel state is formed
contraction pulls are set up. There is
every reason to believe, he stressed,
that the same is true for the basic
substance of life.
Now, he pointed out, if the gel envelope
of the cell is equally thick everywhere
it will be eXerting an equal pull from
all directions and the resulting shape
will be spherical. Local variations in
this thickness would produce distortions,
causing some parts of the cell sub
stance to be thrust outward. These,
he believes are the arms used for en-
gulfng food and for locomotion.
An early indication that a cell is
about to divide" DR.. Lewis said, sis the
retraction. or partial retraction, of these
processes. This is probably due to an
increase in the viScosity Of the super
fetal layer over the body of the cell. The
splitting of cells is to be explained by
the development of thickened, or
denser, equatorial band in this outer
layer. which automatically fattens and
then constricts the cell because of the
increased contractile tension developed
Inside the gel envelope also, DR.. Lewis
moving pictures show, changes in viscos-
ity play significant part in the funda-
mental property of life. Within each
cell are the chromosomes. bundles of the
basic units of heredity. Watched under
the high-powered microscope they oscil-
late back and forth, apparently inde-
pendent of each other This movement
DR.. Lewis told the National Academy
can be explained by the assumption that
each chromosome has two invisible
fibers attached to it. tying it to both
ends of the bundle.
These fibers, he said, are protoplasm
in the form of gel, like the outer en-
velope They are constantly, but ir-
regularly, varying in thickness First
the viscosity of one increases. 1t con-
tracts and pulls the chromosome to
which it is attached toward its side
of the bundle. Then it grows thinner
and relaxes it's pull while the other
fiber exerts a similar pull.
Finally one fiber or the other loses
the tug of war, and the chromosome is
pulled to one end, ready to be incor-
porated In the new cell about to be
formed by the splitting in halves OF the
parent organism.