zoography (zoografi)

[ ogy. zoögyroscope (zō-ō-ji'rō-skōp), п. [ tures of animals in etc. E. H. Knight. II. n. In biol., something like an animal; that which is of the nature of an animal, yet is not an animal in an ordinary sense, and is not the whole of an animal in a strict sense; one of the "persons" or recognizably distinct entities which compose a zoon; that product of any organism, whether of animal, vegetable, or equivocal character, which is capable of spontaneous movements, and hence may have an existence more or le apart from or independent of the parent organism. The biological conception of a zooid is a fundamental one, bordering upon an almost metaphysical definition of what may constitute individual identity or non-identity in a given case: the term covers a multitude of cases which seem at first sight to have little in common, and its use in ordinary zoology and botany is consequently various. The general sense of the word is subject to the following specifications: (a) An ambiguous or equivocal organic body intermediate between a plant and an animal, and not distinctly either one or the other; a micro-organism or microbe not amenable to ordinary cla ification in natural history, as bacteria, bacilli, and micrococci; a protistan, as a moner; one of the lowest protozoans; a protophyte. Such zooids are microscopic, and for the most part of extreme minutene , See the distinctive names, and Monera, Primal i a, Protis. ta, Protophyta, Protozoa. (b) One of certain peculiar cells of multicellular animals and plants which are endowed with special activities, have as it were an individuality of their own, and are capable of a sort of separate existence. Zooids of this cla are mainly germinal or reproductive. The female germ (ovum) and the corresponding male element are respectively types of the whole. They occur under many modifications, which receive distinctive names; many of the smallest and simplest forms are indifferently known as spores. See spore2, spore-formation, oospore, zoospore, sporozooid, antherozoid, sperm a to zooid, and sper 7040 matozoon, with various cuts. The foregoing definitions are independent of any distinction to be drawn between plants and animals; the following are zoological. (c) Any animal organism which has acquired separate existence from another by partition of that other into two or more in the proce es of fi ion, gemmation, and the like. Such zoölogy quently without the origination of a new zoon, are appropriately termed zoöids. The simplest case is when a zoön breaks into two or more pieces, and every piece pro ceeds to grow the part which it lacks, and thus becomes wholly like the organism from which it was detached. Various annelids offer a case in point. Another and large cla of cases is furnished by hydrozoans which suffer segmentation directly, or detach from their main stock various parts, as free medusoids and the like, these zoöids serving to found new organisms. Allman defines the zooid of a hydrozoan as a more or le independent product of non-sexual reproduction. Proliferation or strobilation of parts which may become detached is also well illustrated in the proglottides or deutoscolices which form the joints of tapeworms; these are zoöids in so far as the parent worm is concerned, consisting of detachable genitals containing the elements of a new sexual generation. A similar multiplication by zoöids without generation takes place among tunicates; it is unknown of true vertebrates. One of the most interesting cases is afforded in the parthenogenesis of some insects, as aphids, in which, by a sort of internal gemmation, swarms of zoöidal aphids are budded in succe ion from one another to several removes from the original impregnation. The term zoöid with some writers specifies all these "inferior individuals" which thus intervene in alternation of generation between the products of proper sexual reproduction; and such have been described as "the detached portions of an individual in discontinuous development." (d) Any one of the recognizably distinct persons of a compound organism, whether actually detached or detachable or not; any member of a colonial or social aggregate, as the polypites of a polypidom, the polypides of a polyzoary, and the like. Such zooids offer every degree of separatene or separability. In some cases they are extremely numerous, all alike, and inseparable from the common stock which they fabricate and inhabit, as the members of a coral or seam at. In other cases they are le numerous, and but of a composite sea-anemone of the genus Zoanthus (sec cut slightly connected, and all alike, as the several members there). But the zooids of many hydrozoans, for instance, different in both form and function, in the same individual, for the purpose of division of labor, and the zoöids which thus act as the different organs of one individual are commonly distinguished by name, as go no zoöids, gasterozoöids, dactylozoöids, spirozooids, etc. See the distinctive names. Also zoönite (a mistaken use). IMG:content-2762.png:[blocks in formation] The system of zoolatria , or animal worship, was said to have been introduced into Egypt by King Kekau of the IInd dynasty. W. R. Cooper, Archaic Dict., p. 57.