Evening star., 1937-04-03
STARS, MEN AND ATOMS
Notebook of Science Progress in Field;
Laboratory and Study.
BY THOMAS r. HENRY.

The strange biological phenomenon of
merokineSlS, unique in nature with one
family of tiny insects, has just been re-
ported to the National Academy of
Sciences here by DR.. Kenneth w. Cooper,
Columbia University zoologist.
These little creatures are fathers and
mothers before they are born. They
constitute a species of mites infesting
grass on Long Island. They belong to
a family which, almost alone among
insects, gives birth to living young.
Nearly all insects, as are well known, are
egg layers. The eggs, usually deposited
in enormous numbers, hatch outside the
body of the mother Then the indi-
vidualS go through a series Of meta
orphoses-nymph, larva and the like
before reaching their own reproductive
maturity.
These grass mites, however, are born
fully adult animals. A sack on the body
of the female mite SWells until it is
about 500 times the original body size.
1t is filled with eggs and nutrltlve
fluid Within this sack the eggs hatch
and the new generation passes through
all the ordinary stages of insect meta
morphosis.
Finally, when they are fully mature,
the mother dies, the sack breaks, and
the host of new mites emerges.
This process itself is unique in animal
reproduction. The Long Island mite,
however, goes one step beyond :
1t was long thought that the mites
were striking examples in the insect
world of the phenomenon of partheno-
genesis, or sexual reproduction. Females
isolated as soon as they were born gave
birth to hosts Of young.
Now parthenogenesis is rather widely
distributed among the lower animals
Invariably, except in this one case, all
the offsprings are of one sex, either all
male or all female The supposedly
virgin birth families Of the mites con-
tanned members of both sexes in various
proportions.
1t occurred to DR.. Cooper to watch
their behavior just before birth through
the almost transparent walls of the
maternal sack He found that the en-
tire process of mating takes place before
the brood emerges and that the females
are born on the verge of motherhood.
Two dominant "life lines" of the plant
world are reported as result of expert
ments on photosynthesis in the division
of radiation and organisms OF the
Smithsonian Institution.
Growth of plants, upon which all other
life ultimately depends, requires the
absorption and assimilation of carbon
dioxide from the air under the influence
of light This is the basic physiochem-
ical reaction Of all life.
Now this assimilation takes place
throughout the entire range of visible
light from the deep red to the violet,
but at slightly different rates, depending
on the strength of different wave lengths
in the illumination to which the plant
is exposed.
BY use of the Christensen filter, an
instrument which makes possible this
illumination with very narrow bands of
wave lengths, w. H. Hoover of the
Smithsonian staff has studied the effects
on photosynthesis of the constituent
wave lengths of the entire visible spec
trum.
He finds that there are two points
where the effect of illumination is great
est. One is in the deep red, centering
around the spectrum line produced by
wave length of about $3.50 Angstrom
units, and the other In the blue center
ing around the spectrum line of 400
Angstrom units. An Apgstrom unit Is a
billionth Of a millimet&r and is the unit