The Dickinson press., 1890-11-08
UNDER THE MICROSCOPE.

Ouuor tH0 microscope CneSo living
sponge units appear invarious guiscs and
shapes. Some of them are formless, and,
rs to shape, ever altering masses, rescm.
bling that familiar animalcule of our
pools we know as the amnba. The
members Of the sponge colony form the
bulk of the population. They are i'm.
bedded in the sponge substance; they
wander about through the meshes of the
sponge; they seize food and flourish and
grow; and they probably give origin to
the 'eggs" from which new sponges are
in due course produced.
More characteristic, however, are Ger
tain units of this living sponge colony
which ivein the lining membrane of the
canals. In point of fact, Il sponge is a
kind of Venice, n certain proportion of
whose inhabitants, like the famous queen
Of the Adriatic herself, lived on the
banks of the waterways. Just as in
Venice we find provisions for the deni-
zens of the city brought to the inhabi-
tants by the canals, so from the water,
which, as we shall see, is p%erpetually cir
culating through a sponge, the members
of tho sponge colony receive their food.
Look at a sponge fragment. You per-
ceive half a dozen large holes or SO, each
opening on a little eminence, as it were.
These apertures, bear in mind, we call
oscula. They are the exits of the sponge
dominion. But a close inspection of a
sponge shows that it is riddled with finer
and smaller apertures. These latter are
the pores, and they form the entrances
to the sponge domain. On the banks of
the canal you may see growing plenti-
fully in summer time q green sponge,
which is the common fresh water spe-
cies.
Now it you drop a living specimen of
this species into bowlof water, and put
some powdered indigo into the water,
you may note how tho currents are per
petually being swept in by the pores and
out by the oscula.
ITS NOURIsHMENT.
In living sponge this perpetual and
unceasing circulation of water proceeds.
This is the sole evidence the unassisted
sight receives of the vitality of the sponge
colony, and the Importance of this cir
culation in aiding life in these depths to
be fairly carried out cannot readily be
overestimated.
Let us now SEQ how this circulation is
maintained. Microscopically regarded,
we see here and there, in the sides of the
sponge passages, little air chambers or
recesses, which remind one of the pass
ing places in a narrow canal. Lining
these chambers we see living sponge
units of a type different from the shape
less specks we noted to occur in the
meshes Of the sponge substance itself.
The units of the recesses each consist of
q living particle, whose free extremity is
raised into a kind of collar, from which
projects a lashlike flament known as a
aagellum. This lash is in constant
movement. 1t waves to and fro in the
water, and the collection of lashes we
see In any n chamber acts as d veri-
table brush, which by its movement not
only sweeps water in the pores, but sends
It onward through the sponge, and in
due time sends it out by the bigger holes
OF oscula.
This constant circulation in the sponge
>, discharges more than one important
!. function. For, US already noted, it
ssserves the purpose of nutrition, in that
the particles on which sponge life issup.
ported are swept into the colony. Again,
the fresh currents Of water carry with
them the oxygen gas which is a necessity
Of sponge existence, as of human life.
while, thirdly, waste matters, inevitably
:, alike in snonre and in man NO the rosr,lt
Of living. are swept out of the colony an6
discharged into the sea. beyond. Our bi
Of sponge has thus grown from a mer.
dry fragment into a living reality. I
is a community in which already, low
as it is, the work of life has come to b
: discharged by distinct and fairly special
lied beings.-London Illustrated News