3
village centres which are lying at a small elevation were re
fuges for vegetation and fauna.
On all the rest of the once so fertile island organic life was
obliterated and now, after reclaiming, these areas are an
endless barren plain without a single blade of grass, recalling
the earth m the beginning of the Creation „And the earth
was without form and void".
The sea, in its turn, brought along its own population. Some
few months after the inundation barnacles, algae and other
sessile organisms were already growing on all suitable sub
strata dead trees, houses, meadow fences etc., and on the
innumerable quantities of driftwood which were carried hither
and thither by the waves. Especially when the tide was out,
exposing to the air a zone of about 1 x/i metres in height, mil
lions of white specks, the barnacles, and flapping festoons of
green algae could be observed. Between them, in the open
water, shoals of fish, prawns and shrimps, jellyfish and other
invertebrates were swimming, and bottom-living animals such
as worms, crabs, shellfish etc. settled on and in the mud. It is
even said that seals and porpoises penetrated now and then
into this inland sea and played their graceful caprioles in the
centre of the island.
Now, after the reclaiming of ^Valche^en, a satisfactory
survey of the entire population of the marine phase cannot
be given. The animals which were able to swim actively
ultimately made their escape through the gaps in the dikes.
Only the sessile animals, i.e. those which were firmly attached
to their substratum, and the bottom fauna remained. Inevitably
they had to perish when their natural medium vanished. But
their remains can be studied now at leisure and give us an
idea as to how sea-organisms can settle, live and grow within
a certain amount of time (October 1944October 1945).
That a good many organisms felt quite at home in the
new quarters is easily demonstrated by the unusually large
quantities and the luxuriant growth in which they occurred.
The reasons for this richness are readily understood if we
realize the conditions controlling the animals' distribution in
sea water of a density varying between 30 and 34 °/oo. which
is in constant regular motion, with moderate temperatures, well
aerated and carrying plenty of food.
The common mussel (Mytilus edulis L.) for instance, with
the aid of their byssus threads had attached themselves to
almost every solid submerged object, literally covering trees
and walls, forming regular mats on the ground and hanging
