. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. OVUM. ual production ; the second as coming under the category of alternate generation ; and the Vorticella embryo of the Acineta-fonn either repeats its geninial multiplication, or becomes encysted, and gives rise then by its nuclear division to embryonal production. Other new forms of Infusoria are described by Stein under the names Spirochona gemmipara, Dendrocometes paradoxus, and Lngeno- phrys vaginicola, ampulla, and nassa, in which the mode of reproduction is somewhat similar. These observations at once show the i
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. OVUM. ual production ; the second as coming under the category of alternate generation ; and the Vorticella embryo of the Acineta-fonn either repeats its geninial multiplication, or becomes encysted, and gives rise then by its nuclear division to embryonal production. Other new forms of Infusoria are described by Stein under the names Spirochona gemmipara, Dendrocometes paradoxus, and Lngeno- phrys vaginicola, ampulla, and nassa, in which the mode of reproduction is somewhat similar. These observations at once show the im- portance of the views entertained by some authors as to the share the nucleus may take in new production, and strongly indicate that much still remains to be known from ob- servation of the processes of reproduction among the Infusoria. Should these observations be confirmed, another analogy, in addition to those already observed, will be shown to exist between the organisation and functions of the Protozoa, and those of the lowest plants.* The ten- dency of various other recent researches, to which it has been impossible to refer more particularly in this place, seems to be to show that, in addition to the more common and obvious mode of multiplication by division and gemmation, by which the Infusoria, when vigorous and well nourished, are reproduced, there are other means by which, in dif- ferent circumstances, the more permanent re- production of the species may be secured ; that minute cells are formed within them for that purpose, which may at present be called reproductive cell-germs rather than ova, till a more complete knowledge shall have been obtained of their nature and of the circumstances attending their formation ; and that it is very probable that in the protozoa, as in the simplest plants, the com- bination of the contents of two cells, to all appearance similar, may, as in the process of conjugation, be the necessary preliminary step to the development of t
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