METOPUS. 



[ 502 ] 



MICROCOLEUS. 



BIBL. Ehr. Infus. 477 ; Gosse, Ann. N. 

 H. 1851, viii. 201. 



METO'PUS, Clap, et Lach. A genus of 

 Heterotrichous Infusoria, fam. Bursarina. 



Char. Buccal fossa oblique and elongate, 

 anterior part of the body prolonged ; ante- 

 rior cilia stronger than those of the rest of 

 the surface. M. sigmoides (PI. 52. tig. 11). 

 BIBL. Claparede et Lach. Inf. 254. 

 METRID'IA, Boeck. A genus of Co- 

 pepodous Entomostraca. M. armata, ma- 

 rine. (Brady, Copepoda, i. 79.) 



METZGE'RIA, Raddi. A genus of Pel- 

 lieae (Hepaticae), comprehending Junger- 

 tnanniafurcata, L., and J. pubescent } Sch rank, 

 growing on trunks of trees, rocks, &c. in 

 very moist places. The fronds of both are 

 linear-dichotomous,membranous and ribbed. 

 M.furcata is smooth above, hairy beneath ; 

 M. pubescens hairy on both sides and larger. 

 BIBL. Hook. Br. FL ii. pt. 1. 131 ; Br. 

 Jungerm. pis. 55, 56, & 73 ; Endlicher, Gen. 

 Plant. Supp. 1. 1338; Hofmeister, Vergl 

 Untersuch. 10, pi. 4. 



MICA. This mineral substance, which 

 is often erroneously called talc in the shops, 

 was formerly used for covering mounted 

 objects, but is now replaced by thin glass. 

 It is, however, occasionally useful in apply- 

 ing a red heat to objects, as Diatomaceae, 

 &c., where it is required not to change the 

 position of the object. It often contains 

 crystalline and crystalloidal inorganic mi- 

 neral substances, as metallic oxides, &c., of 

 interesting appearance. 



Thin plates of mica are used also in bring- 

 ing out colours in objects with polarized 

 light. See POLARIZATION, and ROCKS. 



MICRASTE'RIAS, Ag. A genus of 

 Desmidiaceae (Confervoid Algae). 



Char. Cell single, lenticular, deeply 

 divided into two-lobed segments; lobes 

 inciso-dentate (rarely only bidentate), and 

 generally radiating. 



Sporangia spherical, with stout spines 

 (PL 14. fig. 12). 



Numerous British species (Ralfs). 

 M. denticulata (PL 14. fig. 11, undergoing 

 division ; fig. 12, sporangium). Cell cir- 

 cular, surface smooth ; segments five-lobed ; 

 lobes dichotomously divided, ultimate sub- 

 divisions truncato-emarginate, with rounded 

 angles. Length 1-113". Common. 



M. rotata (PL 14. fig. 13). Cell circular, 

 smooth ; segments five-lobed ; lobes dicho- 

 tomously incised, ultimate subdivisions 

 bidentate. Length 1-91". Common. 

 BIBL. Ralfs, Br. Desmid. 68; Lobb, Tr. 



Mic. Soc. 1861; Dixon, Mic. Jn. 1859; 

 Archer, Pritchard's Infm., & Mic. Journ. 

 1862 ; Bailey, Smith. Contr. ; Rabenh. Alg. 

 iii. 187. 



MICROCLA'DIA, Grev. A genus of 

 Ceramiaceae (Florideous Algae), containing 

 one rare British species, M. glandulosa (PL 

 4. fig. 7), with a dichotomously branched, 

 filiform, compressed frond 1 to 2" high, of 

 a bright rose colour. Its fructification con- 

 sists of (1) roundish, sessile involucrated 

 favellae with spores, and (2) tetraspores 

 (tetrahedrally arranged) imbedded in the 

 ramules. 



BIBL. Harvey, Mar. Alg. 160, pi. 22 B ; 

 Phyc. Br. pi. 29 ; Grev. Alg. Br. t. xix. 



MICROCOC'CUS. A genus of Schizo- 

 mycetes, distinguished by the minute or- 

 ganisms being globular instead of linear. 

 The species have been divided into 3 groups. 

 The chromogenous : as M. prodigiosus, 

 which is blood-red, and frequently occurs 

 on Fungi, cooked provisions, red milk, &c. 

 (see BLOOD ON BEEAD) ; M . luteus, cyaneus, 

 violacetis (elliptical), aurantiacus, on cooked 

 potatoes and hard white of egg; and M. 

 chlorinus on egg. The zymogenous, pro- 

 ducing vaiious kinds of fermentation, as 

 M. crepusculum = Moiias c., Ehr. ; M. urea, 

 in Torula-foiTn, 2-8, in urine, converting 

 the urea into carbonate of ammonia, and 

 decomposing hippuric acid. And the patho- 

 genous, by some considered globular Bac- 

 teria, producing contagious diseases : as M. 

 vaccinfe, in vaccine and yariolous matter; 

 M. diphtheriticuSj oval, in twos or more, 

 sometimes in colonies ; M. septicus (Micro- 

 sporow,Klebs), in the tissues and vessels in 

 pyaemia and septicaemia ; M. bombycis, in 

 the intestines of silkworms ; and others, 

 very doubtful, in the blood and sputum of 

 measles, in scarlet fever, typhus, glanders, 

 and syphilis. Collarium, Lk.. seems, at least 

 as regards some species, to be identical. 



BIBL. Butt. Soc. Imp. d'Agric. 2 ser. vii. 

 727; Comptes rendus, 1852, 119; Colin, 

 Beit. i. 109, and ii. 148; Magnin, Bacteries; 

 Hallier, Phytopath. 



MICROCO'DON, Ehr. A genus of Ro- 

 tatoria, belonging to the family Megalotro- 

 chaea. 



Char. Eye single; no carapace; foot styli- 



form. Jaws two, each with a single tooth. 



M. clavuK (PL 44. fig. 8). Body compa- 



nulate, foot equalling or exceeding the body 



in length. Fr. wat. Length 1-288 to 1-216". 



BIBL. Ehr. Infus. p. 395. 



MICROCO'LEUS, Desmaz. (Cht/iono- 



