conversely, the absence of colour said by Forbes and nearly all other writers to
ensue from diminution of light, I have only one series of facts to advance ; but
these appear conclusively to prove that, although intensity of light may, as
averred, engender intensity of tint, the absence of light does not involve its loss
or even its deterioration. The stai'-fishes obtained from a depth of 1260 fathoms
were as brilliantly coloured as if they had lived their lives ill the temperate zone
and the shallowest waters ; whilst, singularly enough, individuals of the same
species dredged up from 100 to 200 fathoms in the fiords of West Greenland
were of a dusky hue. Acmma testudinalis, Natica Grcenlandica, Chiton marmo-
reus, Rippolyte polaris, Boltenia picta, Ophiocoma lellis, CoUrn glacialis, and
Nidlipora purpncrea were of the ordinary vivid tints. Solaster papposa and
Ophiura texturata were alone slightly blanched ; but this effect cannot be attributable
to absence or diminution of light, since the same species occurred in
shallow water, on the Labrador coast, with no greater development of colour.
Lastly, as above stated, the Crustacean brought up by Mr. Torell from 1400
fathoms is described as “ of bright colours.” AVith these facts before us, and
keeping in recollection the evidence that has been adduced to show that the
creatures heretofore discovered at extreme depths are descendants of species
that once flourished in shallow water, it appears reasonable to conclude that
colour is a hereditary character, and that, inasmuch as a creature originally
colourless cannot be made to assume a brighter exterior by subjection to a
brighter sun, so neither can the natural colour of a creature be destroyed by
removal to the opposite conditions. Deterioration of colour may, and undoubtedly
often does occur, as in the case of animals removed from tropical to temperate
regions ; but the cases are not sufficiently numerous to be regarded otherwise
than as exceptional. And when they do occur I cannot help thinking that we
should search for the cause, not in the diminution of light, but in the impaired
vital functions sure to attend removal from normal to abnormal conditions.
Sickly animals, as well as sickly plants, lose their natural colour in tropical countries.
In this case diminution of light can have nothing to do with the result.
The more highly tinted fishes of our own latitudes degenerate in colour when out
of season. And, lastly, there are examples of the reverse action being produced
—that is to say, loss of colour by removal of animals or plants from their
natural habitats in temperate regions to tropical ones. On these grounds I
venture to believe that the colours on the feathers of a bird, the wing of a butterfly,
or the shelly covering of an Echinoderm are as purely hereditary as their
various organs, and that, in artificially produced varieties, we must regard the
condition as to light as only holding equal rank with numerous other secondary
conditions, which produce their effects through the vital functions *-
Having thus described the various agencies on which the bathymetrical distribution
of marine life depends, together with their modes of operation and relations
to each other, it remains for me to prove (what I have heretofore been obliged
to take for granted, in order to avoid endless repetition) that the star-fishes
and other creatures, referred to as having been obtained from great depths, were
captured in a living condition in the midst of their natural haunts.
When we take into consideration the more obvious changes which attend the
removal of a living creature from the deep-sea bed to the surface, we can hardly
fail to perceive that the chances are vastly against the detection of a remnant of
vitality. For, although, as 1 have endeavoured to show, the increase of pressure
which prevails at the bottom of the ocean exercises no more injurious effect on
creatures formed to live under it than the pressure at the sea-level does on terrestrial
animals, and there is every reason to believe that marine creatures in
general, and the lower tribes in particular, can undergo very considerable alterations
of it with impunity, the case becomes totally different when a creature is
suddenly removed from a depth at wliich the pressure is estimated by tons on
the square inch, to one at which it dwindles into a few pounds.
All animal tissues whatever are said to be originally formed of minute cells
which are impervious to gases or fluids save through endosmotic action. But,
since no free gaseous matter can exist permanently at extreme depths, the contents
of such cells must be fluid and of the same, or nearly the same, specific grarity
as the surrounding medium. This is a material character, inasmuch as it enables
* This view derives a singular degree of confirmation from the following facts, for which I am indebted
to Mr. P. L. Sclatcr, the able Superintendent of the Zoological Society’s Gardens. The brilliant
plumage of the Scarlet Ibis {Ibis rubra), a native of Tropical -America, and the equally brilliant scarlet
of portions of tho plumage of the Pine Bullfineh {PyrrJiula emdeatar) and the CrossbiUs {Loxia), both
natives of the northern parts of Europe, fade in an equally marked manner on their removal to this
country; so that we have here presented to us deterioration of the same cohur, in the one instance on
removal of a bird from a tropical to a temperate ehmate, in the other on removal from a boreal to a
temperate climate.
II