. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPIFERA. 47 the interior of which may be observed a ve- sicle that soon becomes organised into nu- merous cells, which constitute the vitelline mass exactly as in the last case. But, arrived at this point, the vitelline mass becomes tu- berculated, assuming the appearance of a rasp- berry, and, instead of a single vitellus, it is found to be an agglomeration of several, each of which contains in its interior a Purkingean vesicle from which a young individual is pro- duced, which is of a totally different form from its
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. rOLYPIFERA. 47 the interior of which may be observed a ve- sicle that soon becomes organised into nu- merous cells, which constitute the vitelline mass exactly as in the last case. But, arrived at this point, the vitelline mass becomes tu- berculated, assuming the appearance of a rasp- berry, and, instead of a single vitellus, it is found to be an agglomeration of several, each of which contains in its interior a Purkingean vesicle from which a young individual is pro- duced, which is of a totally different form from its parent and covered with cilia; by the aid of which it swims freely about in search of a locality where to fix itself. This form of re- production will, however, be more particularly noticed in describing the Sertularian Polypes. Fifth mode, by free gemination and ova com- bined. — This last form of the reproductive process is merely a combination of two of the preceding, propagation being effected by the development of a free gemma, in the interior of which there is formed a divided vitellus. In this case a free embryo becomes organised, and takes the form of a young Medusa, accord- ing to the second mode described above, in the interior of which is contained an ovum with a multiple vitellus, from which numerous ciliated embryos are produced, as in the Ser- tidaria geniciilata hereafter to be noticed. Tubiporidce.— The polypary of the Tubi- Fig. Tubipora musica. pora (fig. 52.)consists of several stages of cy- lindrical tubes placed parallel to each other, or very slightly diverging. These tubes are sepa- rated from each other by considerable intervals, but mutually support each other by the inter- position of external horizontal plates formed of the same dense substance as themselves, by which they are united together, so that a mass of these tubes exhibits an arrangement some- thing like that of the pipes in an organ ; whence the trivial name musica by which the sp
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