. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPlFERA. 25 Fig. Hydra fusca, containing the larva of an insect par- tiaUy digested. o, large superficial cells of the integument; I, mus- cular stratum, the cells of which are very minute, granular, and coloured ; c, villous tunic; d, anus; e, hollow membranous prolongation or foot. (After Corda.) water, however, and allowing it to remain for a little time undisturbed, its real nature be- comes apparent and a series of most interest- ing phenomena present themselves. The mass, which was at first opaque and of a
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPlFERA. 25 Fig. Hydra fusca, containing the larva of an insect par- tiaUy digested. o, large superficial cells of the integument; I, mus- cular stratum, the cells of which are very minute, granular, and coloured ; c, villous tunic; d, anus; e, hollow membranous prolongation or foot. (After Corda.) water, however, and allowing it to remain for a little time undisturbed, its real nature be- comes apparent and a series of most interest- ing phenomena present themselves. The mass, which was at first opaque and of a dense tex- ture, slowly swells and becomes more diapha- nous, apparently by the absorption of the surrounding water into its substance, until, having attained its full dimensions, numerous dimples appear, studding its entire surface, each of which, as it gradually expands, reveals itself to be a cell, the residence of a polype, which, emerging from its abode, displays eight pinnated arms, and the entire Alcyon, thus studded with living flowers, presents a spec- tacle of extraordinary beauty, but if disturbed speedily withdraws from observation and again shrinks into its former shapeless condition. M. Milne Edwards * has thrown considerable light upon the organization of these beautiful structures by his indefatigable researches, the results of which we shall lay before the reader at some length, as they are of great importance in illustrating the economy of the polypiferous zoophytes. The genus Alcyomde (fig. 30) has the poly- pes grouped together in great numbers upon the surface of a soft cylindrical polypary or common body, which consists of two portions. The lower portion (6), which is attached by its base to fuci or other submarine substance, is of a brown colour and firm texture, whilst the upper part is white, membranous, and ex- tremely delicate, divided into branches the summits of which are crowned with elegant polypes (d) of almost microscopic dimensions. Each of th
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