STICTINA. 



[ 738 ] 



STILBACEL 



branches of trees, &c., bursting through 

 from beneath the bark when mature. Stictis 

 (CryptomyceSjBerk.; Propolis, Fr., S. Veg.} 

 versicolor (figs. 697-699) is common on 

 wood ; the upper surface of the open fruit 

 is white, and at length mealy. 



BIBL. Berk. Br. Fl. ii. pt. 2. 214 ; Ann, 

 N. H. vi. 359; Fries, Sum. Veg. 372. 



STIO'TINA, Nyl. A genus of Phyllodei 

 (Lichenaceous Lichens). .Thallus variously 

 lobed or laciniato-lobate ; rliizinae simple; 

 granula gonima of a dark blue-green colour. 

 (Leighton, Lick. FL 108.) 



STICTODIS'CUS, Grev. A genus of 

 Diatomaceae. S. Hardmanianus, in the 

 Monterey deposit. (Grev. Mic. Tr. 1865, 

 98.) 



STIGEOCLO'NIUM, Kiitz. A genus of 

 Confervoid Algee, doubtfully referred to 

 Confervacese, growing mostly in brooks, 

 and composed of delicate branched fila- 

 ments, drawn out into delicate hyaline 

 points; attached to stones and forming 

 masses of a mucous or lubricous character. 

 The jointed filaments are composed of short 

 cells, possessing bright green contents ; the 

 entire contents of a cell are converted into 

 a single spore (with four cilia) and dis- 

 charged (PL 9. fig. 5) ; and the cell-wall is 

 so delicate that it generally vanishes at the 

 same time. Many species are described by 

 Kiitzing, formerly regarded as members of 

 the genus DRAPARNALDIA, which differs in 

 the number of spores produced in each cell, 

 and in possessing large primary filaments 

 with lateral tufts of delicate ones, re- 

 sembling those of Stigeoclonium (fig. 179, 

 p. 271). 



8. protensum (PI. 9. fig. 6). Tufts of 

 filaments 1-36 to 1-60" hi^h, very much 

 branched and elongated ; primary filaments 

 1-1800" in diameter, joints equal or three 

 times as long (Drap. condensata, Hassall). 



S. tenue. Tufts about 1-36" to 1-72" 

 high; filaments 1-2160" in diam., torulose; 

 set above with tufts of abbreviated branch- 

 lets (Drap. tenuis f Hass.) 



S. clongatum. Filaments very slender, 

 1-2880" in diam.; branches erecto-patent, 

 often opposite, subramulose, flagelliform ; 

 joints three or five times as long as broad 

 (Drap. elong. Hass.). 



S. nanum. Filaments highly mucous, 

 very slender, sparingly branched, branches 

 acuminate, not usually ciliate ; cells rather 

 broader than long (Drap. nana, Hass.). 



BIBL. Kiitz. Sp. Alg. 352; Tab. Phyc. 

 iii. pis. 1-11 j Hassall, Br. Alg. p. 118; 



Thuret, Ann. Sc. Nat. 3. xiv. 223, pi. 18 ; 

 Rabenh. Alg. iii. 375. 



STIG'MA. The part of the pistil of An- 

 giospermous Flowering Plants, upon which 

 the pollen rests to produce its pollen-tubes, 

 and where the orifices exist leading to the 

 cavity of the ovary. It is situated either 

 at or near the summit of the style or its 

 branches ; or, when this is absent, it is ses- 

 sile on the ovary. The surface of the stigma 

 is clothed with papilliforni or short tubular 

 cells, from which a tenacious secretion 

 exudes at the period when the ovules are 

 prepared to receive the pollen-tubes. At- 

 tached by this adhesive fluid and often 

 grasped by the papillae the pollen-grains 

 produce their tubes, which make their way 

 between the papillae to descend through 

 the conducting tissue of the style to the 

 placenta (PI. 40. fig. 30). These papilli- 

 form cells in a young state often form 

 favourable subjects for the stud} r of the pro- 

 toplastic cell-contents, and also of the fluid 

 colouring-matter. The forms of the stigma 

 are exceedingly varied and sometimes very 

 elegant; and some of those covered with 

 coloured hairs form beautiful microscopic 

 objects. In the Order Compositae, its cha- 

 racters are used for the systematic division 

 of the numerous genera. 



STIGMA' US, Koch. A genus of Trom- 

 bidina (Acarina). Legs seven-jointed, ce- 

 phalothorax with transverse line ; no eyes. 

 S. cruentus, very minute. (Koch, Uebers. ; 

 Murray, EG. Ent. 124.) 



STIGMAPH'ORA, Wallich. A genus 

 of Diatomaceae. 



Char. Frustules free, naviculoid j valves 

 lanceolate, loculate ; loculi with central and 

 marginal puncta ; marine. India. 



BIBL. Wallich, Tr. Mic. Soc. viii. 43; 

 Rabenht. Alg. i. 258. 



STIG'MATA OF ANIMALS. See SPIRA- 

 CLES. 



STIGMATIDTUM, Mey. A genus of 

 Graphidei (Lichenaceous Lichens). Apo- 

 thecia brownish, punctiform or elongate, 

 immersed, hypothecium colourless. (Leigh- 

 ton, Lick. Flora, 412.) 



STIGONEMA, Ag. A supposed genus 

 of Oscillatoriaceae, founded upon what has 

 proved to be the thallus of a genus of 

 Lichens. See EPHEBE. 



STILBA'CEI. Afamily of Hyphomyce- 

 tous Fungi, growing upon decaying animal 

 or vegetable matter, or on bark or leathery 

 leaves. Characterized by a receptacle com- 

 posed of conjoined filamentous or hexagonal 



