MICROCYSTIS. 



[ 503 ] 



MICROTHECA. 



blastm, Kiitz.). A genu8 of Oscillatoriaceee 

 (Coiifervoid Algae), with fronds forming 

 strata on moist ground, paths, mud, &c. 

 These plants may be described as bundles 

 of Oscillatoria-fil&meiits enclosed in a com- 

 mon gelatinous sheath, which is simple or 

 irregularly dichotomously branched, and 

 forms twisted interwoven masses. The 

 structure of the filaments appears to be 

 identical with that occurring in OSCILLA- 

 TORIA, described under that head ; the fila- 

 ments oscillate : the mode of origin of the 

 enclosing sheath is obscure j but it would 

 appear to be formed of the gelatinous half- 

 dissolved outer membranes of the enclosed 

 filaments. No formation of spores or goni- 

 dia has been described. M. repens, Harv. 

 (PI. 8. fig. 9 a, the open end of a sheath), 

 is very common on damp paths, &c., its 

 sheaths are branched ; M. anguiformis, 

 Harv., occurs on the mud of brackish 

 pools; its sheaths are said to be simple. 

 M. gracilis, Hassall, said to be found in 

 similar situations, has no character attached 

 to it. 



BIBL. Harvey, Mar. Alg. 227, pi. 26 D ; 

 Phyc. Br. pi. 249; Hassall,^. 260, pi. 70; 

 Kiitz. Tab. Phyc. i. pis. 54-58. 



MICROCYS'TIS, Kiitz. A genus of 

 Palmellaceae (Confervoid Algae), composed 

 of crowded minute spherical cells, enclosed 

 in a common envelope, forming solid fami- 

 lies. M. protog&nita (PI. 3. fig. 12), bluish 

 green, in long-kept water. 



BIBL. Kiitz. Sp. Alg. 208; Tab. Phyc. 

 pis. 8, 9 ; Rabenh. Alg. ii. 61. 



MICROGLE'NA, Ehr. A genus of In- 

 fusoria, family Monadina, E. 



Char. Tail absent ; body truncated in 

 front, with a single flagelliform filament ; 

 one or two red eye-spots present. Fresh- 

 water. 



Probably the spores of Algae. 



M. pimctifera (PI. 31. fig. 43 a). Body 

 yellow, ovate, subconical, attenuate poste- 

 riorly, two red eye-spots accompanied by 

 a blackish frontal spot ; length 1-620". 



M. monadina (PI. 31. fig. 436). Body 

 ovate, equally rounded at both ends, bright 

 green ; eve-spot red and single ; length 

 1-1150 to* 1-620". 



BIBL. Ehr. Infus. 25 ; Kent, Inf. 403. 



MICROGONID'IA. See MACROGONIDIA. 



MICROGRO'MIA, Hert. A genus of 

 Reticularian Rhizopoda. The pseudopodia 

 of different individuals unite, so as to pro- 

 duce colonies. ( Hertwig, Arch. mik. An. 

 x. Suppl. 1.) 



MICROHALO'A, Kiitz. A genus of Pal- 

 mellaceae (Confervoid Algae), consisting of 

 microscopic gelatinous patches, floating in 

 water, crowded with minute green gonidia. 

 M. Ichthyoblabe (quite distinct from CLA- 

 THROCYSTIS) occurs in Britain ; and Has- 

 sall's Sorospora virescens belongs here. Pro- 

 bably a Chlorococcus. 



BIBL. Kiitz. Sp. Alg. 207; Tab. Phyc. 

 pis. 6, 7 j Hassall, Alg. 326 ; Rabenh. Alg. 

 lii. 60. 



MICRO'MEGA, Ag., = SCHIZONEMA pt. 



MICROM'ETER. See INTRODUCTION, 

 p. xxviii, and MEASUREMENT. 



MICROPE'RA,Lev. A genus of Sphas- 

 ronemei (Stylosporous Fungi), of which 

 one species is described as British, M. dru- 

 pacearum (Cenanyium Cerasi, Junior, Fr., 

 Sphceria dubia, Pers.), growing on dead 

 branches of the cherry-tree. It forms 

 whitish tubercles which split the bark trans- 

 versely, composed of somewhat cylindrical 

 conceptacles, conjoined at the base, the 

 white mealy ostiole projecting; the linear 

 spores are yellowish and curved at the 

 apex. 



BIBL. Berk, and Broome, Ann. N. H. 

 2 ser. v. 380 ; Leveille, Ann. So. Nat. 3 se"r. 

 v. 283 ; Br. Flora, ii. pt. 2. 211. 



MICROP'ORA, Gray,= Membranipora 

 pt. (Hincks, Polyz. 173.) 



MICROPOREL'LA, Hincks, = Lepralia 

 pt. (Hincks, Polyz. 204.) 



MI'CROPYLE (of Animals). See OVUM. 



MICROSCOPE. The first Section of 

 the INTRODUCTION consists of remarks upon 

 the microscope and microscopic apparatus. 



MICRO-SPECTROSCOPE. See SPEC- 

 TROSCOPE. 



MICROS'PORA, Thuret,= <Wm>pt 



MI'CROSPORES. The small kind of 

 spores produced by Lycopodiaceae and Mar- 

 sileaceae in contradistinction to megaspores 

 or maorospores. When sown, they pro- 

 duce sperm-cells and spermatozoids. 



MICROTHAM'NION, Nag. A genus 

 of Cha&tophoracese. 



Char. Filaments much branched, rigid, 

 jointed, narrow ; joints longer than broad, 

 slightly tumid. Propagation by zoogonidia. 

 Freshwater. 



BIBL. Rabenh. Alg. iii. 365. 



MICROTHE'C A, Ehr. A marine organ- 

 ism of doubtful nature. 



It consists of yellow, flattened, rectan- 

 gular (side view) bodies, with four equi- 

 distant spines projecting from each end ; 

 the colour arises from the contents; no 



