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resolution of the body into numerous uninucleate zoospores (amcx bulx or flagelluhe) which may conjugate as gametes; plasmodium formation unknown; encystment (in " resting cysts " or " hypnocysts ") See also:

COMMON

common. Without a knowledge of the See also:

HISTORY

history it is impossible to distinguish a naked Lobose from the Amoebula (pseudopodiospore) of a Myxomycete or Proteomyxan. As to the name, Dujardin included the thecate Lobosa, the See also:

FILOSA (A. Lang)

Filosa, and the Reticularia or See also:

FORAMINIFERA

Foraminifera(q.v.). The latter had already received the name Foraminifera (for their shells) from d'See also:

ORBIGNY, ALCIDE DESSALINES

Orbigny; and as it is impossible to See also:

SEPARATE

separate naked from thecate Lobosa we have merged his Amoebina (Amibiens) in the larger group. The Filosa were removed by See also:

Lang from the Reticularia; in See also:

HABIT (through the French from Lat. habitus, from habere, to have, hold, or, in a reflective sense, to be in a certain condition; in many of the English senses the French use habitude, not habit)

habit and test they are inseparable from the Lobosa; and though their cytoplasm approximates to that of Reticularia, their ectosarc is much less granular, though not See also:

FREE

free from granules as stated by Lang. The See also:

MAJORITY (Fr. majorite; Med. Lat. majoritas; Lat. major, greater)

majority of Rhizopoda are fresh-See also:

WATER

water forms, some occurring in the film of water on mosses, among Sphagnum, or about the bases of grass-haulms; many, however, are exclusively marine. The aquatic forms generally may lurk among Confervae or higher weeds, or See also:

lie in the bottom of decomposing or excre, mentitious See also:

MATTER

matter in still or slow-flowing See also:

WATERS, TERRITORIAL

waters. Of these some may become temporarily pelagic, floating up by the formation of See also:

gas vacuoles (containing probably See also:

CO2) in the cytoplasm. It is easy to verify this by placing Amelia (fig. 1, 7) in S. drop of water on a See also:

glass See also:

COVER (from the Fr. convert, from couvrir, to cover, Lat. cooperire)

cover and inverting this over a glass See also:

RING (O.E. hring; a word common to Teutonic languages; and probably cognate with the Lat. circus, Gr. KtpKOS or KpLKOS, Skt'. chakra, wheel, circle, cf. also " harangue "); in art, a band of circular shape of varying sizes, made of any material and used f

ring; the Arcellasink to the free See also:

CONVEX

convex surface of the drop and See also:

ESCAPE (in mid. Eng. eschape or escape, from the O. Fr. eschapper, modern echapper, and escaper, low Lat. escapium, from ex, out of, and cappa, cape, cloak; cf. for the sense development the Gr. iichueoOat, literally to put off one's clothes, hence to sli

escape from this most unnatural position by secreting gas-vacuoles; when they See also:

FLOAT (in O. Eng. floc and flota, in the verbal form f eotan; the Teutonic root is flut-, another form of flu-, seen in " flow," cf. " fleet "; the root is seen in Gr. a-M e, to sail, Lat. pluere, to rain; the Lat, fluere and fluctus, wave, is not connect

float up to contact with the glass cover, so as to See also:

TOUCH (derived through Fr. toucher from a common Teutonic and Indo-Germanic root, cf. " tug," " tuck," O. H. Ger. zucchen, to twitch or draw)

touch it by the convex back of the shell, they put forth See also:

long pseudo-podia which attach themselves to the glass and, by their See also:

con-See also:

TRACTION (Lat. trahere, to draw)

traction turn the See also:

animal over, so that it can crawl over (i.e. under) the glass.

See also:

AMOEBA

Amoeba (Entamoeba) histolytica, Schaudinn, is the cause of tropical See also:

DYSENTERY (from the Gr. prefix Ova-, in the sense of " bad," and Evmpov, the intestine)

dysentery and hepatic See also:

ABSCESS (from Lat. abscedere, to separate)

abscess in See also:

man. See also:

PELOMYXA

Pelomyxa (fig. 1, 5–6) is remarkable for containing symbiotic bacteria. Zooxanthellae (symbiotic See also:

green cells—See also:

ALGAE

Algae or Flagellates) occur in several See also:

SPECIES

species; and Paulinella contains two sausage-shaped See also:

BLUE (common in different forms to most European languages)

blue-green bodies, " chromatophores," which are probably symbiotic Cyanophyceae. The shell, even when not a simple membrane, has always a continuous inner membrane of a complex nitrogenous substance containing See also:

SULPHUR

sulphur, allied to keratin and termed pseudochitin. The See also:

OUTER

outer layer when See also:

PRESENT

present is composed of little hollow prisms (Amelia, fig. 1, 7), See also:

sand, or inorganic matter first swallowed by the animal (See also:

DIFFLUGIA (L. Leclerc)

Difflugia, Pseudodijiugia), sometimes partially digested (Lecquereuxia), or else of plates secreted as " reserve plates " within the cytoplasm of the animal Cyphoderia (fig. 6, B), Quadrula, Nebelia, Euglypha (See also:

FIGS

figs. 4, 6, A), &c. In Quadrula irregularis alone are the plates said to be calcareous; elsewhere they are always siliceous and simply refractive; so that the See also:

SILICA

silica is probably hydrated (See also:

OPAL

opal). The See also:

CEMENT (from Lat. caementum, rough pieces of stone, a shortened form of caedimentum, from caedere, to cut)

cement is possibly of silicified pseudochitin. This material is often permeated by a ferric See also:

OXIDE

oxide or See also:

HYDRATE

hydrate, even when it is not coloured rusty See also:

brown.

Shell formation of the membranous test is by simple surface-See also:

EXCRETION (Lat. ex, out of, cernere, cretum, to separate)

excretion; under budding we describe its accomplishment in the aggregated shells. The " See also:

PYLOME

pylome," or See also:

APERTURE (from Lat. aperire, to open)

aperture for the protrusion of the See also:

PROTOPLASM

protoplasm, is usually single. There are two pylomes at opposite poles in several Filosa (Ditrema), hence See also:

UNITED

united by some authors into a distinct See also:

FAMILY

family (fig. 7, 1, 5, 11), and in the gelatinous theca of Trichosphaerium (fig. 5) are numerous permanent pylomic pores. The See also:

NUCLEUS (Lat. for the kernal of a nut, nux, the stone of fruit)

nucleus is variable in See also:

FORM (Lat. forma)

form and See also:

CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character. In Amoeba binucleata two nuclei are always present; and some genera are permanently plurinucleate (Pelomyxa, See also:

ARCELLA (C. G. Ehrenberg)

Arcella, fig. 1, 7). It often gives forth fragments into the cytoplasm, the " chromidia" of R. Hertwig, which, as in Foraminifera (q.v.), may See also:

PLAY

play an important See also:

PART

part in reproductive processes. The contractile vacuole (there are two in Amelia, fig. 1, 7) in actively progressing Rhizopods always discharges at the hinder end.

Absent or sluggish in marine forms, it is of See also:

CONSTANT, BENJAMIN (1845-1902)

constant occurrence in all fresh-water Rhizopods except Pelomyxa. The pseudopods vary greatly in type. In Amoeba princeps (fig. 1, 4) they are See also:

mere promontory-like extensions of the body; in A. radiosa (fig. 1, 1–3) and Trichosphaerium (fig. 5) they are distinct slender processes, tapering, and either See also:

blunt or finely pointed at the See also:

APEX

apex; in Pelomyxa (fig. 1, 5, 6) as in A. (Lithamoeba) See also:

DISCUS (Gr. &oEor, disk)

discus (fig. 2) they are " eruptive, " hemispherical, formed apparently by the rupture of the ectoplasm, and the outpouring of the endoplasm which at once differentiates a clear outer layer as a new ectoplasm; in Amoeba limax during progression the body is roughly See also:

OVAL (Lat. ovum, egg)

oval with the apex truncated posteriorly and the wide anterior end forming a single anterior M. See also:

SCHULTZE, MAX JOHANN SIGISMUND (1825-1874)

Schultze, in three stages of equal binary fission during fifteen minutes; a, nucleus; b, contractile vacuole (after M. Schultze). 4, Amoeba princeps, Ehr.; a, nucleus; b, c, vacuoles; See also:

food vacuoles shaded (after See also:

AUERBACH, BERTHOLD (1812-1882)

Auerbach).

5, 6, Pelomyxa palustris: 5, a small example in. in See also:

DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter, moderately extended; 6, a portion more highly magnified; a, ectosarc; b, vacuoles; c, d, pseudopods formed by eruption and containing endosarc; e, vesicles containing a See also:

SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of glycogen; f, nuclei; the numerous little pods are symbiotic bacteria. 7, Arcella vulgaris: a, shell; b, cytoplasm; c, lobose pseudopods; d, d, d, 3 nuclei; e, one of the contractile vacuoles; the dark shaded circles represent bubbles or gas vacuoles. 8, Cochliopodium pellucidum: a, " vesicular " nucleus, with dense central See also:

mass or " karyosome " (a frequent type of Protistic nucleus). (From Lankester.) See also:

PSEUDOPOD, PSEUDOPODIUM

pseudopod. Progression chiefly takes See also:

PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place by a See also:

ROLLING

rolling over of the anterior end (fig. 3—see also AMOEBA) ; but it may take place by the See also:

EXTENSION (Lat. ex, out ; tendere, to stretch)

extension of a pseudopod, its See also:

ATTACHMENT

attachment at the tip, followed by its contraction to pull up the See also:

REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest of the See also:

ANI (anc. Abnicum)

ani=mal; this is well shown in the thecate species. Another mode is that of A. radiosa (fig. i, I-3), which can See also:

roll over on the tips of its stiff pseudopods. The pseudopods of the Filosa (figs. 6, 7) are branched, but less See also:

rich in granules, and less viscid than those of Foraminifera; they rarely anastomose, and never coalesce to form perforated plates. A See also:

PROCESS

process whose relations to reproduction are not fully made out is that of " plastogamy," where two or more individuals unite completely by their cytoplasm, the nuclei remaining distinct; it may be temporary or permanent: in the latter See also:

case See also:

CONE (Gr. Kwvos)

cone cone f, food particles; conc., concretions, insoluble in dilute HCI and KHO, soluble in strong HCl; n, nucleus. determining, of course, a much more rapid increase of See also:

SIZE

size than that due to growth. Thanks to the labours of F.

Schaudinn, we now know the full See also:

LIFE

life cycles of at least See also:

HALF

half a dozen species; previously we only knew with certainty of two modes of fission-equal constriction (Amoeba—fig. I, 1—3) and bud-fission (Dijjlugia). As in other See also:

SARCODINA

Sarcodina, chromidia, or fragments of nuclear substance budded off from the nucleus into the endoplasm, play an important part in many reproductive processes. Equal binary fission is common. In the thecate forms, e.g. Difflugia, Euglypha (fig. 4), this is replaced by bud-fission; half the cytoplasm passes out through the pylome, and becomes A x x' a b c From Jenning's Contributions to the Study of the Behavior of See also:

LOWER

Lower Organisms, by permission of the See also:

Carnegie Institution of See also:

Washington, D.C. invested with its covering there; the enclosed " reserve " skeletal elements pass to the surface in See also:

order, so that the pylome of the new shell faces that of the old; the See also:

ORIGINAL

original nucleus divides in situ and one daughter nucleus passes into what we may See also:

CALL (from Anglo-Saxon ceallian, a common Teutonic word, cf. Dutch kallen, to talk or chatter)

call the bud-cytoplasm; the two daughters of the original See also:

CELL (from Lat. cella, probably from an Indo-European kal —seen in Lat. celare, to hide; another suggestion connects the word with Lat. cera, wax, taking the original meaning to refer to the honeycomb)

cell, which we may call the " bud-See also:

SISTER

sister " and the " stock-sister " respectively, now separate. In the plurinucleate forms a true bud-formation takes place, nucleate masses of cytoplasm being constricted off at the surface. A simultaneous resolution into uninucleate cells may affect the multinucleate species (or the multinucleate See also:

state of habitually uninucleate species); this is termed schizogony. In Trichosphaerium (fig. 5) it occurs at the See also:

close of two dcd' 2 b P From The See also:

Cambridge Natural History, after Schaudinn, vol. i., Protozoa, by permission of See also:

MACMILLAN

Macmillan & Co.

Ltd. brood-cells are •amoebulae (pseudopodiospores) (fig. 5, 4) which grow into the multinucleate B type, with a nonspiculate theca (fig. 5, 5). The resolution of the B type is preceded by rapid multiplication of the nuclei by mitosis (fig. 5, 7), and the uninucleate cells are 2-flagellate zoospores (fig. 5, 9). These pair with zoospores of a different brood to their own (fig. 5, to) (i.e. they are exogamous gametes); and the See also:

FUSION

fusion cell (fig. 5, II) so formed is the starting-point of the A type (fig. 5, 12). Brood formations by resolution of a multinucleate individual has been observed or conjectured in Amoeba, &c.

A formation of numerous pseudopodiospores within Pelomyxa has been repeatedly described, and these have been seen to conjugate equally, the zygote becoming multinuclear. But the possibility of the alleged reproductive cells being parasites has not yet been fully excluded. Chlamydophrys stercorea is a small Filose, occurring in the faeces of several mammals, but only forming its characteristic shell out- D See also:

side the body; plastogamic monstrosities are frequent. The nucleus degenerates, and is expelled with some plasm. The chromidia remain inside the shell, and differentiate or aggregate into about eight nuclei; the cell is then resolved into as many 2-flagellate which escape as isogamous exogametes. The becomes surrounded by a brown cyst. When From See also:

EUGENE

Eugene Penard, Faune rhizopodique du Bassin du L€man. B, Sphenoderia lenla. I, Animal, lateral view; 2, same from above; 3, shell, lateral view; 4, shell, oral view of the pylome; 5, See also:

OPTICAL

optical See also:

section through empty shell and pylome; 6, nucleus; 7, surface view of pylome (dotted lines represent its opposite.side as seen at a lower See also:

FOCUS (Latin for " hearth " or " fireplace ")

focus). distinct periods in the life See also:

cycle which we may call A and B; the individuals of the A See also:

period being distinguished by the C A B From Calkin's Protozoa, by permission of the Macmillan Co., New See also:

York. Fm. 4.—Bud-fission of Euglypha alveolata.

A, passing out of secreted plates to surface of bud. B, bud completely invested ; nucleus preparing to See also:

DIVIDE

divide by mitosis. C, D, later stages. presence of radiating spicules of MgCO3 in the gelatinous theca; the resolution of period A is simple (fig. 5, 3) and the uninucleate swarmers, zygote swallowed by a mammal it develops, and the See also:

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary form is found in the excreta. Centropyxis aculeata is closely allied to Difugia: It divides by fission and also at the end of a cycle by schizogony, the j 5 6 7 S 9 offspring being amoebulae. In some these acquire a shell directly; in others a second brood division into four takes place, and it is only then that shells are formed. The latter conjugate as See also:

MALES

males with the former as See also:

FEMALES

females; and the fusion cell encysts within the, approximated shells; it emerges as a naked amoeba after a period of rest, forms a shell and assumes the type of the species. Other types of reproduction are known, Amoeba coli, an inhabitant of the gut of man, showing an endogamous pairing of closely related nuclei similar to that of Actinosphaerium (see HELIoz0A). See also:

CLASSIFICATION (Lat. classis, a class, probably from the root cal-, cla-, as in Gr. icaMce, clamor)

CLASSIFICATION Lobosa.—W. B. See also:

Carpenter.

Cytoplasm with a clear ectosarc, not wetted by the See also:

MEDIUM

medium; pseudopods never finely branching, usually rounded at the apex; nucleus single or multiple; shell (" test," " theca ") absent, gelatinous, membranous or of cemented granules of ingested sand, &c., or plates secreted in the endosarc. Selected genera: § I. Naked Amoeba (q.v.) (" Amibe," Bory), with the subgenera Dactylosphaerium, Hertwig and Lesser (fig. 1, 1-3), with slender, pointed pseudopods; Lithamoeba, Lankester, always containing inorganic granules (fig. 2). Pelomyxa, Greeff (fig. 1, 5, 6), with blunt, eruptive pseudopods and numerous nuclei, T in. or more in diameter when contracted. Arcuothrix, See also:

CLAPAREDE, JEAN LOUIS RENA ANTOINE EDOUARD (1832–187o)

Claparede and See also:

LACHMANN, KARL KONRAD FRIEDRICH WILHELM (1793-1851)

Lachmann, with one or more slender, very See also:

MOBILE

mobile, flagelliform pseudopods as well as the lobose ones. § 2. Test gelatinous, perforated by pseudopods: Amphizonella, Greeff ; Trichosphaerium, See also:

Schneider (fig. 5). § 3.

Test membranous: Cochliopodium, Hertwig and Lesser (fig. 1, 8). § 4. Test " chitinous," shagreened : Arcella, See also:

Stein (fig. I, 7). § 5. Test of ingested particles: Diflugia, Leclerc; Centropyxis, Stein; Lecqueureuxia, Schlumberger (shell material of diatomaceous tests fused into sausage-shaped masses). § 6. Test of secreted siliceous or chitinous plates: Quadrula, F. E. Schultze. (In Q. irregularis the plates are said to be calcareous.) Filosa.—A.

Lang. Cytoplasm without definite ectosarc ; pseudopods branching, tapering to fine tips, somewhat granular; test present in all known species and varying as in the Lobosa. Selected genera: § 1. Test membranous: Gromia, Dujardin (pro parte) ; Mikrogromia, Hertwig ; Diplophrys, See also:

BARKER, EDMUND HENRY (1788–1839)

Barker (fig. 7, I); Ditrema, See also:

ARCHER, WILLIAM (1856— )

Archer; Amphitrema, Archer (fig. 7, 11); the last three have a mouth-like aperture (pylome) at either end of the test. § 2. Test of ingested or incrusted particles: Pseudodifflugia, Schlumberger; Diaphorodon, Archer (fig. 7, 12). § 3. Test of secreted plates: Euglypha, Dujardin (figs. 4, 6, A); sphenoderia lenta (fig.

6, B) ; Paulinetllaa, Lauterborn. bellosen Thiere (ed. 2), i., " Protozoa " (1901); and See also:

MARCUS

Marcus Hartog, " Protozoa," in Cambridge Natural History, i. (1906). Of the older literature we need only cite F. Dujardin, " Sur See also:

les organismes inferieurs," See also:

Ann. Sc. Nat. Zool. iv. (1835), and " Zoophytes, infusoires " (1841). (M.

End of Article: RHIZOPODA

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