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inference could be arrived at, namely, that such swimming-bladders would
Again, pieces of wood retained for an hour or two at a depth of a thousand
fathoms are said to have become so increased in density as to “ sink like stones.”
Captain Scoresby relates an example of a boat having been dragged doivn by a
whale to such a vast depth that the wood of which it was formed sank like a
stone, not only immediately after its recovery from the sea, but “ for a year
afterwards.” Here, then, it would appear that the whale must have descended
as deep as the boat, or probably deeper, inasmuch as the latter was attached
to it by the whale-line and harpoon. Other instances have at various times
been recorded of harpooned whales haring dived down vertically to immense
depths, and, in some cases, haring been killed by coming into forcible contact
with the bottom!
But, notwithstanding the vast muscular power possessed by the gigantic
Cetaceans, and the momentum attained by their bodies when diving with
extreme speed, we should hardly he justified in looking to them for evidence
tending to prove that life can be maintained at depths exceeding 500 fathoms.
This will perhaps be rendered more apparent when it is recollected that the
whale is not constituted to live at any great depth, and that its specific gravity
is such as to he in equilibrium with the surrounding element almost immediately
below the surface. Hence, even at the moderate depth of 500 fathoms, its body
would be exposed to such a degree of compression as would at once paralyse, if
not destroy, life. Thus, if we take the case of a medium-sized whale, say 50 feet
long, and with an average diameter of 10 feet, the total pressure on the surface
of the body would amount to upwards of 11,000 tons. I t is supposed that
the peculiar conformation of the Cetacean skin, throughout the substance of
which the blubber is secreted, enables the creature to sustain a degree of
pressure that would otherwise be intolerable—a pressure stated as “ sometimes
amounting to a ton upon every square inch ” *. But, inasmuch as the whole of
the observations on tbe depths to which whales have been supposed to penetrate
are based on the quantity of line run out, and its direction on entering the water,
it is much more likely that, as in the case of soundings taken where deep-seated
currents prevail, the direction is changed from a vertical to a horizontal one,
* See Professor Carpenter’s ‘ Zoology ’ (London, 1857: 2 vols.), vol. i. p. 239.
long before the extreme depths were reached at which these tremendous pressures
exist*.
In the case of pieces of wood and meat, and corked bottles containing air,
which have been sent down to great depths in order to demonstrate the effects
of pressure, it is evident that precisely those conditions are present which are
never to be met with in creatui-es constituted to live under it. In short, they
prove too much ; for they prove clearly that, in defiance of all obstacles, a state
of equilibrium is rapidly engendered between the interior and the exterior of the
wood, the mutton, and the bottles, and that whensoever this takes place no
fui’ther change is experienced. I f suddenly submerged, that is to say, before
the pressure has time to overcome the resistance of the cellular and fibrous
tissues of the two first and of the cork employed in the last, diminution of bulk
and consequent compression of the structure must inevitably result ; but, on the
other hand, if the submergence be gradual, the diminution iu bulk is by no
means a necessary consequence, and the change brought about is a simple displacement
of a lighter medium by a heavier, according to a well-known law of
fluids. The example so often cited of the cork being at first forced inwards, and
subsequently redriven into the neck of the bottle so as to close it as effectually
as before, clearly shows that its cellular tissue has undergone compression and
redilatation. Hence these experiments can only be regarded as illustrating
phenomena which are not confined to extreme depths in the ocean, but may be
seen in operation in a modified degree in ev’ery piece of floating organic matter
around us.
The faculty possessed by some ground-living fishes of accommodating themselves,
in certain localities, to depths greatly in excess of those usually frequented
by them is veiy remarkable. Thus, several of the Cod tribe have a vertical
range from 10 to 200 or even 250 fathoms, whilst a large number of species
inhabit depths ranging from 10 to 100 fathoms. But, according to M. Pouilletf,
certain fishes have been obtained by him from a depth of 550 fathoms, that is,
* Since the operation of getting an “ up-and-down ” sounding is attended with considerable diffi-
culty, even -when undertaken Avith. a sinker of tlio shape best fitted to descend vertically, and a line
little thicker than an ordinary pencil, it may readily he imagined how vastly the chances of an incorrect
eatimate, both with regard to deptli and dii-ection, must he increased, Avhere the line employed is three-
quarters of an inch thick, and a wounded monster is fast to the end of it.
t ‘ Elemens do Physique Expérimentale/ tom. i. p. 187.