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elements in order to construct their shells, we are warranted in supposing they
may also apply the elements not needed for that purpose to the nutrition of their
soft parts; especially since the remaining elements are those which, when united,
constitute the proteine-compound of which their soft parts are invariably composed.
AVe may endeavour to establish a definite line of demarcation between
the two great kingdoms of nature ; but if we unbiassedly examine the life-history
of the simplest forms on either side—as, for example, a cell of Collosphmra and a
cell of Navimla— vie shall find ourselves reduced to the admission that the vaunted
boundai-y-line is empirical. I f this be admitted, the grand distinction between
the animal and the plant is destroyed—at least in the lowest tribes—and we
discern in the liberation of a portion of the oxygen and carbon of the carbonic
acid, of the hydrogen of the water, and the nitrogen of the atmospheric air, a vital
act heretofore regarded as characteristic ouly of the vegetable kingdom. In
short, the same process yields shell-material and food ; and we discover that the
last link in the series is derived, not from the vegetable world as we have heretofore
been taught to believe, but from the inorganic. On the other hand, if this
be denied, we have no alternative but to assume that the lower the creature the
less need is there for special organs to perform special functions, and that the
humble Ehizopod or Polycystine may digest, secrete, excrete, and (for all we
can adduce to the contrary) think into the bargain !
Although the discovery, at extreme depths, of creatures devoid of visual organs
would simply indicate that life is in no degree dependent on light, or on the
previous manifestation of plant-life said to be inseparable from it, it is impossible
to regard the occurrence, under similar conditions, of any of the more highly
organized forms whose morphological relations involve the possession of organs
of vision, without perceiving that upon this single fact hangs the question whether
living creatures were originally constituted to live beyond the influence of light,
or became gradually habituated to live at extreme depths. For it is manifest
that the detection of the most rudimentary eyes would prove that the creatures
possessing them had originally lived in shallow water, and that they had slowly
accommodated themselves to the new and abnormal conditions by which they
were surrounded—the sense of sight failing under the absence of the natural
stimulus, and the organs of sight either degenerating or becoming obliterated
from disuse, during a succession of generations.
The caves of Carniola, Adelsberg, Kentucky, and other localities furnish us
with numerous examples of blindness in animals living beyond the influence of
light, and enable us to trace the transition, from the simple loss of nervous sensibility
to the partial or entire occultation of the external organs of sight, which
is observable as the animals recede from the outer world and take up their abodes
where the darkness is more or less complete. But inasmuch as blindness involves
the presence, however rudimentary or degenerate, of a special set of organs, we
should not be warranted in regarding creatures as originaUy created to pass their
lives in the gloomy depths of these caves, or in any other position beyond reach
of hght, unless all trace of rudimentary visual organs was absent, and there was
distinct evidence that the types to which such creatures belonged occurred elsewhere
with those organs developed.
The identity of the Ophiocomæ obtained from an extreme depth in the North
Atlantic with the Ophiocoma granulata of shallow water, although affording presumptive
evidence that their ancestors, like their contemporaries met with on our
own coasts, were not specially created to live in that position, is by no means a proof
of the fact. TheOphiuridæ do not possess the so-called “ eye-spots” of theAsteriadæ
and Solasteriæ ; and even if they did, the proof of these spots being true organs
of vision supplied with nervous ganglia is far too feeble to be generally accepted.
But, fortunately for the fate of the question, the Ophiocomæ referred to are not the
most highly organized creatures that have been discovered at great depths, inasmuch
as a “ Crustacean of bright colours ” is reported to have been brought up
from 1400 fathoms, by Mr. ToreU the director of the recent Swedish Expedition
to Spitzhergen *. In the absence of a detailed description of this Crustacean, it
would be premature to speculate on the indications afforded by its visual organs.
But since the Crustaceans possess these organs without any exceptionf, the fact is of
the highest value, as affording additional proof that creatures originally constituted
to live in shallow water may gradually become acclimatized and live under the
extraordinary conditions prevalent at extreme depths in the ocean.
AVith regard to the effect of light on the production of colour in animals, and,
* No official report of this expedition having appeared up to the present time, my information is
derived from a letter which appeared in the ‘ Athenæum ’ of Dee. 7, 1861, w’hich bears the stamp of
perfect authenticity.
t See ‘ Anatomy of Tnvertebratn/ Sicbold, English edition, vol. i. p. 325.