The Cook County herald. [volume] (Grand Marais, Minn.) 1893-1909, 1897-09-25
NEED NO cyl S.
Creatures That See Through Their
Skins
Some Curious Facts CONCERNING the.
Lower Orders of Animal Life 8
snatls, sluss and rs
4 ssl5 valves.

an error, 1t we are to believe DE-. NAgel, a
recent German experimenter. Many
creatures without eyes can see, at last
they can distinguish perfectly well be-
tween light and darkness, ard even be-
tween different degrees Of light. This
is the lowest degree OF seeing, to be
sure, but still tits really sight, and diff
fers scarcely more from the visions of
some insects that possess eyes than
this does from our own clear sight.
Creatures that see without eyes see
by means of their skins. All skins,
says Dr.. Nagel, are potential eyes; that
lis, they are sensitive to Light. In an
imals that have eyes the sensitiveness
has been highly localized and greatly
increased $50 that man, for instance
has q retina very sensitive to light.
and an expanse OF ordinary. skin which
possesses q sensitiveness to light so
slight that it is hardly conscious Of it.
Yet the E III is sensitive in: some de-
gree, as is proved by the fact that it
sunbu1ns that is, light may cause a
disturb ance in the pigment Of the skin
just as it does in that of the eye. & In
the eye the disturbance is accompanied
by a nervous change which sends a
telegraphic message along the optic
nerve to the brain. In the skin, too,
there are nerves, and there are mes
sages, also, but their tidings imprint
no image on the mind; they simply
express discomfort cry out sun
burn d 4
But in many eyeless creatures the:
lack Of eyes is in part made up by in-
creased sensit iveness Of: i the whole
skin surface to light. Darwin long ago
noticed that the cart worms, although
they have no eyes, will suddenly with
draw into their holes on the approach of
a Lighted candle. Some creatures seem
more sensitive to suddenly increased
light, others. to sudden diminution. IF
a number OF oysters, kept in vessel
together, are found to be open, they
will shut all at once if a dark object
comes between them and the light.
Another bivalve called Psammodia.
has long, whitsh, transparent tubes
which protrude from the sand in which
it lies buried. II they are suddenly IL
Illuminated, they contract, and the
brighter the light the greater the con-
traction. IF a number Of them be car
ried into direct sunlig BIT, they hasten to
bury themselves in the sand; or, If
there is no sand, they move restlessly
to and fro in the water until they are
exhausted.
T. general, DR.. Nagel finds that
creatures which respond to sudden
shadows are those that live in strong
shells, while those affected by a sud-
den increase Of light live in sand or
mud, from which they emerge occasion
ally. IN both cases the sensitivenesso Of
the skin to changes Of light serves to
protect the animal. q
How does the skin acquire this PEE
culiar sensitiveness? It will be best
for the non-expert to suspend judg
ment, since even the scientists do moi
agree on this point. It may be that it
is a universal and rudimentary prop
erty of all skin, and that animals with
eyes have lost it in agreater orsless de-
gree, because they have no further need
for it. This is one view. Or it may
be that this property has been devel-
oped in eyeless creatures just because
they are eyeless and need 1T. That is
another view. Those who favor the lat
ter opinion point to the fact that some
OF the creatures which now have skins
sensitive to the light are probably de-
scendants OF creatures with skins not
SO sensitive; in these instances the
sensitiveness must have been recently
developed. Snails are sensitive, but
their relatives, the slugs, are not; this
looks as If the former had acquired the
faculty. However this may be, DR..
Nagel's study Of these curious and out
of-the-way facts is certainly interest
ing, and may lead in the future to nad-
vance in our knowledge Of the mechan-
ism of sight. Boston Journal.
| How to Serve Potatoes 9
Old potatoes boiled whole, peeled and
covered with 6 sauce made by cooking
together half pint Of milk, table
spoonful Of butter and one Of flour, are
better thus prepared than when served
in any other fashion. New potatoes are
waxy until late in the season, and
should not be given to children or to
persons Of delicate digestion. The old
IfaShioro1 q. fIo<t r. :, ~, ~ x.