Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . s, sometimes in the form oflong chains, sometimes branched, sometimesexpanding to form a spherical bag, as in thewell-known Volvox globator, which was longdeemed a single individual of a peculiarspecies. New spherical groups of Volvoces * XVIII. f Beccaria, who first saAV a Polygastrian in the act of dividing, supposed it to betwo in copulation. Saussure, in 1765, first recognised its real character. J This analogy I pointed ont in ilhistration of the cleavage-process o
Lectures on the comparative anatomy and physiology of the invertebrate animals : delivered at the Royal College of Surgeons . s, sometimes in the form oflong chains, sometimes branched, sometimesexpanding to form a spherical bag, as in thewell-known Volvox globator, which was longdeemed a single individual of a peculiarspecies. New spherical groups of Volvoces * XVIII. f Beccaria, who first saAV a Polygastrian in the act of dividing, supposed it to betwo in copulation. Saussure, in 1765, first recognised its real character. J This analogy I pointed ont in ilhistration of the cleavage-process of the ovaof the Mednsa in my Lectures on Generation, delivered in 1840. It is alhidedto in the following passage in Dr. ISI. Barrys Memoir on the Nucleus of the Animaland Vegetable Cell, 8vo. 1847. Between the appearances presented by themammiferous germ during the passage of the ovum through the oviduct, and cer-tain infusoria, including the Volvox globator as figured by Ehrenberg, the resem-blance first mentior^ed by Professor Owen is so remarkable that we cannot avoidthe beUef, that the same process operates in rOLYGASTRIA. 29 are thrown oli into the interior of the parent monadiary, which isrent open to allow them to escape, as in,fiy. 15. Another mode of generation is by gemmation or the developmentof buds, which in some species, as Cheroma, grow out of the forepart of the body, and in others, as Vorticella, from the hind part,near the stem, or from tlie stem itself, from which the young animalsoon detaches itself. In most Vorticellidce, as in Carchesium andEpistylis, the small liberated end of the body opposite the mouth isprovided with a circle of vibratile cilia, so long as the individual swimsfreely: but these disappear when the pedicle is developed. In the Zygnema, a freshwater confervoid Alga, the filaments ofwhich it is composed are developed, separately, by a linear multipli-cation of cells ; the filaments then approximate, protuberances areformed from corre
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1850
