protoxid, protoxide (protoksid)

[ πρῶτος, first, + E. oxid.] That member of a series of oxids which contains a single oxygen atom combined with a single bivalent atom or with two univalent atoms: applied only to oxids which are not strongly basic or acid. protoxylem (pro-to-zīʻlem), n. [ under various forms. The cla Gregarinida represents parasitic forms, one or two-celled, e entially like the ova of Metazoa. The cla Infusoria comprehends an enormous number of minute, nearly always microscopic, animalcules, found in infusions, inhabiting both fresh and salt water, sometimes parasitic, but mostly leading an independent fixed or free life. There are many groups of these, as the ciliate, flagellate, cho a no flagellate, and suctorial infusorians, among them the most complex organisms which are commonly included under Protozoa, as the Noc tiluca, for example. With or without some of the lowest disputed forms, and with or without the sponges, Proto zoa have been very variously subdivided, almost every author having his own arrangement. A so-called moner, an amœba, a foraminifer, a radiolarian, a gregarine, and an infusorian respectively exemplify as many leading types of Protozoa. One division is into A stomata and Stomatoda, according to the absence or presence of a mouth. Another is into Monera and Endoplastic a, according to the absence or presence of a nucleus, the latter being again distinguished as Myxopoda and Mastigopoda, according to whether the locomotory organs are temporary pseudopods or permanent cilia or flagella. A third is into Gymnomyxa and Corticata, according to the absence or presence of a distinguishable ectoplasm. (1) The Gym nomyxa are separated into 7 cla es: Proteomyxa (indefinable), Mycetozoa (often regarded as plants), Lobosa (ordinary amœbiforms), Labyrinthulidea, Heliozoa (sun animalcules), Reticular i a (the foraminifers), and Radiola ria. (2) The Corticata are divided into 6 cla es: Sporo zoa (gregarines and many others), Flag ell at a, Dinoflagel lat a, Rhynchoflagellata, Ciliata, and Acinetaria, the last five being as many cla es of infusorians. This is the cla if i cation presented in the latest edition of the Encyclopædia Britannica. By Saville Kent the Protozoa (including sponges) are divided into 4 prime "evolutionary series, not exactly coincident, however, with any recognized zoological groups, called Pan to stomata, Disco stomata, Eustomata, and Poly stomata. (See these words.) Also called Hypozoa, Oözoa, Plast i do zoa. Compare Primal i a, Protist a, Protophyta. See cuts under Actinosphærium, ameba, Euglena, Foraminifera, Globigerinidæ, Gregarinidæ, Infusoria, Noctiluca, Paramecium, radiolarian, and sun - animalcule. protozoal (prō-to-zō'al), a. [ Bütschli's cla ification of these protozoal forms. IMG:content-1160.png:[blocks in formation] The Century Dictionary and Cyclopedia The individualized protozoanal stage has become confined to the earliest periods of existence. Stand . Nat . Hist ., I. 60. protozoary (pro-to-zō'a-ri), n.; pl. protozoaries (-riz). [F. protozoa ire, They exhibit the rhythmically contracting vacuoles which are specially characteristic of protozoic organisms. W. B. Carpenter, Micros., § 225. 2. In geol., containing the earliest traces of life. - Protozoic schists, the name given by Barrande to the lowest division of the fo iliferous rocks of Bohemia. See primordial. protozoön, protozoum (prō-tō-zōʼon, -um), n.; pl. protozoa (-a). [NL [NL.,