Online Encyclopedia

FLAGELLATA

Online Encyclopedia
Originally appearing in Volume V10, Page 464 of the 1911 Encyclopedia Britannica.
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FLAGELLATA, the name given to the Protozoa whose dominant phase is a " flagellula," or cell-body provided with one, few or rarely many long actively vibratile, cytoplasmic processes. Nutrition is variable: (r) " Holozoic "; food taken in by ingestion, by amoeboid action either unspecialized or at one or more well-defined oral spots, or through an aperture (mouth); (2) " Saprophytic " ; food taken in in solution through the general surface of the body; (3) " Holophytic "; food-material formed in the coloured plasm by fixation of carbon from the medium, with liberation of oxygen, in presence of light, as in green plants. Fission in the " active " state occurs and is usually longitudinal. Multiple fission rarely occurs save in a sporocyst, and produces microzoospores, which in some cases may conjugate with others as isogametes or with larger forms. (megagametes). " Hypnocysts " to tide over unfavourable conditions are not infrequent, but have no necessary relation to reproduction. Many have a firm pellicle which may form a hard shell: again a distinct cell-wall of chitin or cellulose may be formed: finally, an open cup, " theca," of firm or gelatinous material may be present, with or without a stalk: such a cup and stalk are often found in colonial species, and are subject to much the same conditions as in Infusoria. The nucleus is simple in most cases; but in Haemoflagellates it is connected with a second nucleus, which again is in immediate relation with the motile apparatus; the former is termed the " trophonucleus," the latter the " kineto-nucleus." As reserves the protoplasm may contain oil, starch, paramylum, leucosin (a substance soluble in water, and of doubtful composition), proteid granules. In the holophytic forms the cytoplasm contains specialized parts of more or less definite form,29 30 °I
End of Article: FLAGELLATA
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FLAGELLANTS (from Lat. flagellare, to whip)
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