place.
Rings are formed round its body, from ten to fifteen in number. These
gradually deepen, until at length it is literally cut up into a number
of segments, which rest one upon the other--their upper margins
becoming elevated, and divided into eight lobes. It is, in fact, a
pile of cup-shaped pieces, very loosely connected together. A little
later, these pieces free themselves successively, and the sedate
polype disappears in a company of sprightly young medusae. These
beings, indeed, still differ in some respects from the adult animal;
but the differences gradually vanish, and we have the perfect
jelly-fish as the final result of this extraordinary series of
transformations.

Similar observations have been made respecting other tribes amongst
the lower animals, and some interesting generalisations have been
founded upon them, into which, however, it is not our present purpose
to enter.

The _Acalephae_ are the principal agents concerned in the production of
the beautiful phenomena of phosphorescence. The minute species--mere
gelatinous specks--swarm at times by countless myriads in the waters
of the ocean, and make its surface glow with 'vitalised fire.' The
waves, as they curl and break, sparkle and flash forth light, and the
track of the moving ship is marked by a lustrous line. 'In the torrid
zones between the tropics,' says Humboldt, 'the ocean simultaneously
develops light over a space of many thousand square miles. Here the
magical effect of light is owing to the forces of organic nature.
Foaming with light, the eddying waves flash in phosphorent sparks over
the wide expanse of waters, where every scintillation is the vital
manifestation of an invisible animal world.' Beneath the surface
larger forms are seen, brilliantly illuminated, and lighting up the
mystic depths of the sea. Fiery balls and flaming ribbons shoot past;
and submarine moons shine with a soft and steady light amidst the
crowds of meteors. 'While sailing a little south of the Plata on one
very dark night,' says Mr Darwin, 'the sea presented a wonderful and
most beautiful spectacle. There was a fresh breeze; and every part of
the surface, which during the day is seen as foam, now glowed with a
pale light. The vessel drove before her bows two billows of liquid
phosphorus, and in her wake she was followed by a milky train. As far
as the eye reached, the crest of every wave was bright; and the sky
above the, horizon, from the reflected glare