. The Protozoa. Protozoa. GENERAL SKETCH 57 Simple division frequently leads to colony-formation through incom- plete separation of the daughter-individuals. Four general types of these colonies are met with among the Protozoa. Adopting Haeckel's terms, they may be designated according to their general structure as (l) gregaloid, (2) spheroid, (3) arboroid, and (4) catenoid. A gregaloid colony is an aggregate of Protozoa having a round, ellipsoidal, or indefinite shape, and usually with a gelatinous basis in which the single individuals are variously distributed. The colonies may be formed by
. The Protozoa. Protozoa. GENERAL SKETCH 57 Simple division frequently leads to colony-formation through incom- plete separation of the daughter-individuals. Four general types of these colonies are met with among the Protozoa. Adopting Haeckel's terms, they may be designated according to their general structure as (l) gregaloid, (2) spheroid, (3) arboroid, and (4) catenoid. A gregaloid colony is an aggregate of Protozoa having a round, ellipsoidal, or indefinite shape, and usually with a gelatinous basis in which the single individuals are variously distributed. The colonies may be formed by incomplete division of the individuals or by partial union of two or more adults (Fig. 24). A spheroid colony is a globu-. Fig. 26. — Codosiga cymosa Sav. K., an arboroid colony of Choanoflagellida. [Kent.] lar, ellipsoidal, or cylindrical aggregate in which the individual cells form a superficial layer in a common gelatinous matrix. When these superficial cells are closely packed together into an almost continuous layer as in Volvox, Magosphcera, or Uroglena, they are extremely sug- gestive of certain stages in developing Metazoa (Fig. 25). An arbo- roid colony is a tree- or bush-like aggregate arising by the dendritic or dichotomous branching of a primary stalk or a gelatinous matrix. Such colonies are usually attached by the base to some foreign object and often resemble hydroids or Bryozoa (Fig. 26). They may, how- ever, as in Dinobryon, be free-swimming. A catenoid colony is fili- form or chain-shaped, arising from the union of cells end to end, or. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Calkins, Gary N. (Gary Nathan), b. 1869. New York, The Macmillan company; London, Mamcillan & co. , ltd.
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