The Key West citizen., 1954-09-21

ASSOCIATIVE FFets Sefenee HsPvTIwt
WOODS HOLE, Mass. B-Mys-
terious Clocks" operating in living
things are q challenge to some Of
the scientists at the Marine Bio
logical Laboratory here.
Certain humans can "set mental
clocks" to waken at q certain time
of morning. How do their clocks
work!
Many kinds Of living things be-
have as though regulated by inner
or biological clocks ticking off
time with amazing accuracy.
Take fiddler crabs, the inch
long ones named because of their
fiddle holding shape. They are
being studied by DR.. Frank A.
Brown Jr., Northwestern Univer-
| sity, who spends his summers here.
At dawn or just before they turn
dark in color, the better to run on
dark beaches where they live. At
night they turn pearly gray in
color. Is II, Just a response to sun.
light or lack Of II?
No, DR.. Brown finds, for If the
crabs are kept in q Photographic
dark room, under a steady amount
Of light and temperature, they will
still change color at dawn and
dusk, telling time as well as a
man-made clock.
The crabs respond to tides, too,
turning darkest at low tide. Even
in the closed room they will change
color according to actual high and
low tides on the beaches where
they once lived. They are perfect
tide charts.
Fiddler crabs from two different
beaches, where the times of high
or low tides are different, will obey
the tide chart for their own
beaches, though living far from
home.
They show q 24-hour change for
the sun cycle, a 1214-hour change
for the tide cycle. In tide, they are
obeying a moon or lunar cycle,
for the moon is 4 main controller
of earthly tides.
| Is their biological clock some
thing which is built-in, running at
constant speed according to me-
taboliSm or the speed Of their life
cycles? Or is it governed by ply
sical forces connected with the
earth's rotation, perhaps by some
force which man doesn't yet know
can affect living things?
DR.. Brown subjected the crabs to
different degrees of temperature.
An astonishing thing happened if
he chilled them down to near
Ifreez'ing for six hours, then
warmed them up again. The chill
ling stopped their clocks for six
hours. When they were warmed up
again, they began following the
same cycles Of regular change
but now they were nearly six hours
slow!
That makes it look as though
their clocks are built inside. But
that's by no means the full strange
story.
Not long ago one of DR.. Browns
assistants flew to San Francisco
with a batch of crabs, and put
them in a room there with constant
light and temperature. Another
batch was packed up the same
way for travel, but kept here and
placed in the same kind of room.
Those flown to the West Coast be-
came three hours late in time
and in all physical forces con-
nected with the earth's rotation
compared with those remaining
here.
On the first day, the crabs on
both coasts changed colors at ex-
actly the same time according to
dawn and dusk, and tidal changes
here.
The next day, the crabs in San
Francisco slipped a half hour be-
hind their East Coast cousins"
But this was only temporary.
During the next seven days while
they stayed in California, they con-
tinued to get dark or light almost
simultaneously with the crabs in
Woods Hole.
They didn't adjust their "clocks'
to the West Coast, and while they
stayed in California, they kept on
signalling the time Of low tide on
their native beach on Cape Cod.
This proved they could still
measure the 12A-hour tide cycle
and 24-hour sun cycle accurately
even though they had been flown
to the West Coast and had, by
flying. changed by three hours in
sunlight time - the same gain
your watch would show If you hew
from East to West.
In the long run their clocks may
be influenced by outside forces, DR..
Brown believes. He is devising ex-
lperiments to learn the possible in
fluence Of slight barometic
changes, differences in gravitation,
even differences in cosmic ray
radiation, to which all living things
are exposed.
OYSTERS show q similar kind of