deep, in
which Mount Everest would be engulfed. There is enormous pressure in
such depths; even at 2,500 fathoms it is two and a half tons on the
square inch. The temperature is on and off the freezing-point of fresh
water (28 deg.-34 deg. Fahr.), due to the continual sinking down of cold water
from the Poles, especially from the South. Apart from the fitful gleams
of luminescent animals, there is utter darkness in the deep waters. The
rays of sunlight are practically extinguished at 250 fathoms, though
very sensitive bromogelatine plates exposed at 500 fathoms have shown
faint indications even at that depth. It is a world of absolute calm and
silence, and there is no scenery on the floor. A deep, cold, dark,
silent, monotonous world!

Biological Conditions

While some parts of the floor of the abysses are more thickly peopled
than others, there is no depth limit to the distribution of life.
Wherever the long arm of the dredge has reached, animals have been
found, e.g. Protozoa, sponges, corals, worms, starfishes, sea-urchins,
sea-lilies, crustaceans, lamp-shells, molluscs, ascidians, and fishes--a
very representative fauna. In the absence of light there can be no
chlorophyll-possessing plants, and as the animals cannot all be eating
one another there must be an extraneous source of food-supply. This is
found in the sinking down of minute organisms which are killed on the
surface by changes of temperature and other causes. What is left of
them, before or after being swallowed, and of sea-dust and mineral
particles of various kinds forms the diversified "ooze" of the
sea-floor, a soft muddy precipitate, which is said to have in places the
consistence of butter in summer weather.

There seems to be no bacteria in the abysses, so there can be no
rotting. Everything that sinks down, even the huge carcase of a whale,
must be nibbled away by hungry animals and digested, or else, in the
case of most bones, slowly dissolved away. Of the whale there are left
only the ear-bones, of the shark his teeth.

Adaptations to Deep-sea Life

In adaptation to the great pressure the bodies of deep-sea animals are
usually very permeable, so that the water gets through and through them,
as in the case of Venus' Flower Basket, a flinty sponge which a child's
finger would shiver. But when the pressure inside is the same as that
outside nothing happens. In adaptation to the treacherous ooze, so apt
to smother, many of the active deep-s