Young Folks' Library, Volume XI (of 20) eBook

This eBook from the Gutenberg Project consists of approximately 349 pages of information about Young Folks' Library, Volume XI (of 20).
which are ascribed to ancient earth-throes without imagining for a while that the power of modern earthquakes is altogether less.  But when we consider fairly the share which time had in those ancient processes of change, when we see that while mountain ranges were being upheaved or valleys depressed to their present position, race after race, and type after type appeared on the earth, and lived out the long lives which belong to races and to types, we are recalled to the remembrance of the great work which the earth’s subterranean forces are still engaged upon.  Even now continents are being slowly depressed or upheaved; even now mountain ranges are being raised to a new level, tablelands are in process of formation, and great valleys are being gradually scooped out.  It may need an occasional outburst, such as the earthquake of August, 1868, to remind us that great forces are at work beneath the earth’s surface.  But, in reality, the signs of change have long been noted.  Old shore-lines shift their place, old soundings vary; the sea advances in one place and retires in another; on every side Nature’s plastic hand is at work modelling and remodelling the earth, in order that it may always be a fit abode for those who are to dwell upon it.






It is not merely on land that this phenomenon of phosphorescence is to be seen in living forms.  Among marine animals, indeed, it is a phenomenon much more general, much more splendid, and, we may add, much more familiar to those who live on our coasts.  There must be many in the British Isles who have never had the opportunity of seeing the light of the glow-worm, but there can be few of those who have frequented in summer any part of our coasts, who have never seen that beautiful greenish light which is then so often visible, especially on our southern shores, when the water is disturbed by the blade of an oar or the prow of a boat or ship.  In some cases, even on our own shores, the phenomenon is much more brilliant, every rippling wave being crested with a line of the same peculiar light, and in warmer seas exhibitions of this kind are much more common.  It is now known that this light is due to a minute living form, to which we will afterward return.

But before going on to speak in some detail of the organisms to which the phosphorescence of the sea is due, it will be as well to mention that the kind of phosphorescence just spoken of is only one mode in which the phenomenon is exhibited on the ocean.  Though sometimes the light is shown in continuous lines whenever the surface is disturbed, at other times, and, according to M. de Quatrefages, more commonly, the light appears only in minute sparks, which, however numerous, never coalesce.  “In the little channel known as the Sund de Chausez,” he writes, “I have seen on a dark night each stroke of the oar kindle, as it were, myriads of stars, and the wake of the craft appeared in a manner besprinkled with diamonds.”  When such is the case the phosphorescence is due to various minute animals, especially crustaceans; that is, creatures which, microscopically small as they are, are yet constructed more or less on the type of the lobster or cray-fish.

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Young Folks' Library, Volume XI (of 20) from Project Gutenberg. Public domain.
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