. Animal biology. Zoology; Biology. g6 PROTOZOA tions of a nervous system; sensitive areas, which function as sense organs; and supporting parts, which form a sort of skeleton (Fig. 34). The food of protozoans consists of organic matter, both vegetable and animal, Hving and dead. Their metaboUsm is, in general, similar to that described for the ameba or the Paramecium. Because of the size of the animals the study of digestive enzymes is difficult, and there is httle precise knowledge. Protozoans certainly digest proteins, have been shown to be able to use emulsified fats, and also are able to
. Animal biology. Zoology; Biology. g6 PROTOZOA tions of a nervous system; sensitive areas, which function as sense organs; and supporting parts, which form a sort of skeleton (Fig. 34). The food of protozoans consists of organic matter, both vegetable and animal, Hving and dead. Their metaboUsm is, in general, similar to that described for the ameba or the Paramecium. Because of the size of the animals the study of digestive enzymes is difficult, and there is httle precise knowledge. Protozoans certainly digest proteins, have been shown to be able to use emulsified fats, and also are able to use certain starches. In addition to fission, or binary division, and sporulation, protozoans sometimes exhibit a third type of asexual reproduction known as gemma- tion, or budding. In this case individuals of smaller size than the parent grow out from it like buds and when developed break loose, later growing to the same size as the individual which produced them (Fig. 35).. A S Fig. 35.—Gemmation, or budding, in Ephelota gemmipara (Hertwig). {After Hertwig, in Morphologisches Jahrbuch, vol. 1.) A, organism on stalk, showing two types of ten- tacles, suctorial and prehensile, the latter with spiral ridges on the surfaces. B, an indi- vidual showing the formation of buds, into each of which extends a portion of the nucleus. These buds become detached and free-swimming; they possess cilia on one side but later develop tentacles and become attached. X 120. Bacteria, although they are one-celled organisms, are not protozoa. They are considered as more planthke than animal-like. Bacteria differ from protozoa chiefly in lacking a definite nucleus, the chromatin mate- rial being distributed throughout the cell, and in possessing cellulose in their cell wall. They are usually very minute and may be spherical, rodlike, or spiral in shape. Many bacteria are free-Uving, many are parasitic, some are pathogenic (disease producing). Bacteriology is the science dealing with bacteria. 113.
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