Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/880

856 PROTOZOA [FLAGELLATA. made erroneously to external parasitic organisms, which have nothing iu common with the Sporozoa. This was the case in regard to a fungoid growth in human hair the so-called " chignon Gregarine. " The Silk-worm disease known as "pebrine" lias also been attributed to a Gregarine. It seems probable that the parasitic organism which causes that disease is (as is also the distinct parasite causing the disease known as " flaecidezza " in the same animals) 0113 of the Sehizomycetes (Bacteria). No disease is known at present as due to Sporozoa, although (e.g. , the Klossia ckitonis) they may lead to atrophy of the organs of the animals vhi<-h they infest, in consequence of their enormous numbers. Coeciuui and Sareoeystis are stated to occur in Man. CLASS II. FLAGELLATA, 1 Ehrenberg. Characters. Corticata in which the dominant phase in the life- history is a corticate flagellula, that is. a nucleated cell-body pro vided with one or a few large processes of vibratile protoplasm. Very commonly solid food particles are ingested through a distinct cell-mouth or aperture in the cortical protoplasm, though in some an imbibition of nutritive matter by the whole surface and a nutri tional process chemically resembling that of plants (holophytic), chlorophyll being present, seems to occur. Conjugation followed by a breaking up into very numerous minute naked spores is frequent in some ; as also a division into small individuals (microgonidia), which is followed by their conjugation with one another or with big individuals (macrogonidia) and subse quent normal growth and binary fission. Many have a well-developed cuticle, which may form collar-like outgrowths or stalk-like processes. Many produce either gelatinous or cnitin-like shells (cups or ccenoecia), which are connected so as to form spherical or arborescent colonies ; in these colonies the proto plasmic organisms themselves produce new individuals by fission, which separate entirely from one another but are held together by the continuity, with those already existing, of the new shells or jelly-houses or stalk-like supports produced by the new individuals. A single well-marked spherical nucleus, and one or more contractile vacuoles, are always present iu the full-grown form. Often, besides ingested food-particles, the protoplasm contains starch granules (amylon nucleus), paramylum corpuscles, chromato- phors and chlorophyll corpuscles, some of which may be so abundant as to obscure the nucleus. One or two pigment spots (stigmata or so-called eye-spots) are often present at the anterior end of the body. SUB-CLASS I. Lissoflagellata, Lankester. Never provided with a collar-like outgrowth around the oral pole. ORDER 1. MONADIDEA, Biitschli. Characters. Lissoflagellata of small or very small size and simple structure ; often naked and more or less amceboid, sometimes forming tests. Usually colourless, seldom with chromatophors. With a single anterior large flagellum or sometimes with two additional paraflagella. A special mouth-area is often wanting, sometimes is present, but is never produced into a well-developed pharynx. Fam. 1. RHIZOMASTIGINA, Biitschli. Simple mouthless forms with 1 to 2 flagella ; either permanently exhibiting a Gymnomyxa- like development of pseudopodia or capable of passing suddenly from a firm-walled into a Gymnomyxa-like condition, when the flagdla may remain or be drawn in. Ingestion of food by aid of the pseudopodia. Genera. Mastigameeba, F. E. Schultze; Ciliophrys, Cienkowski (65 1 ; biniorplM, Graber; Actinomonas, Kent; Trypanosoma, Gruby (parasitic in the blood of Frogs and other Amphibia and Reptiles, I- " XX. 21, 22). The Rhizomastigina might all be assigned to Fi tin- Proteomyxa, with which they closely connect the group of Flagellata. The choice of the position to be assigned to such a form as Ciliophrys must be arbitrary. Fam. 2. CERCOMONADINA, Kent. Minute oblong cell-body which posteriorly may exhibit amoeboid changes. One lar^e anterior flagellum. Mouth at the base of this organ. Reproduc tion by longitudinal fission and by multiple fission producin" spores in the encysted resting state. Genera. Cenoiiumas, Duj. (Fig. XX. 32, 33); Herpetomanas, S. Kent; (Mcomaruu, Kent (-Monas, James Clark; Pseudositora Cienkowski, Fig. XX. 29, 30, 31) ; Ancyromonas, S. K. Farn. 3. COUOXOZCINA, Kent. Small colourless monads similar to Oikoinonas in structure, which secrete a fixed gelatinous or membranous envelope or cup. Genera. Cudonoeca, James Clark ; Plntytha>ca, Stein. Fam. 4. BIKCECIXA, Stein. Distinguished from the last family the fact that the monad is fixed in its cup by a contractile thread-like stalk ; cup usually raised on a delicate stalk Genera. Hicosceca, J. Cl. ; Poteriodcndron, Stein. ,! m Ut8 r r r! S W n rk (9) ha8 bct;n P rett > closcl y followed in tlie diagnosis of the gioups of Hagellata atid the enumeration of genera here given. FIG. XX. Flagellata. 1. Chlamydomnnas pulviscuhtg, Ehr. (Zygoselmis, From.); one of the Phy toraastigoda ; free-swimming individual, a, nucleus; 6, contractile vacuole ; c, starch corpuscle; d, cellulose investment; e, stigma (eye-spot). 2. Resting stage of the same, with fourfold division of the cell-contents. Letters as before. 3. Breaking up of the cell-contents into minute bitlagellate swarm-spores, which escape, and whose history is not further known. 4. Syncrypta volvox, Ehr. ; one of the Phytomastigoda. A colony enclosed by a common gelatinous test c. a, stigma; b, vacuole (non-contractile). 5. Uroglena volvnx, Ehr. ; one of the Monadidea. Half of a large colony, the flagellates embedded in a common jelly. 6. Chlorogonium cuchlorum, Ehr. ; one of the 1 hytomastigoda. a, nucleus; b, contractile vacuole; c, starch grain ; d, eye-spot. 7. Chlorogonium euchlorum, Ehr., one of the Phytomastigoda. Copulation of two liberated microgonidia. a, nucleus; b, contractile vacuole ; d, eye-spot (so-called). 8. Colony of Diiwbryon scrtularia, Ehr. ; x 200 ; one of the Monadidea. 9. Iliemnto- coccux palustris, Girod (= CMamydococcus, Brauii, Protococcus Colin), one of the Phytomastigoda; ordinary individual with widely separated test, a, nucleus ; b, contractile vacuole ; c, amylon nucleus (pyrenoid). 0. Dividing resting stage of the same, with eight fission products in the common test e. 11. A microgonidium of the same. 12. Phalangterium consociatum, Cienk., one of the Choanoflagellata ; x 325. Disk-like colony. 13. Euylena viridia, Ehr. ; x 300 ; one of the Euglenoidea. a, pigment spot (stigma) ; b, clear space ; c, paramylum granules; d, chromatophor (endochrome plate). 14. Gonium perforate, O. F. Mullcr; one of the Phytomastigoda. Colony seen from the flat side. 300. a, nucleus ; b, contractile vacuole ; c,, amylon nucleus. 15.

Dinobryon scrtularia, Ehr. ; one of tlie Monadidea. a, nucleus ; 6, con-