STAURASTRUM. 



C 734 ] 



STAUROCARPUS. 



character of rice-flour. In the Leguminosae, 

 and the pea (fig. 6 b*, p. 28), the granules 

 are oblong, the striae distinct, and the hilum 

 radiate. In the Potato the starch-granules 

 (fig. 21) are larger than any of the above j 

 they are numerous and closely packed in the 

 cells (fig. 20) . Among the more remarkable 

 forms of starch are the large grains of the 

 Cannes (fig.25),Jfw$(fig.24),andinost of the 

 Zingiberaceae (fig. 19). Some East-Indian 

 Arrow-root (fig. 18) has compound grains 

 of large size (mostly detached in the pre- 

 pared farina). True West-Indian Arrow- 

 root, from Maranta arundinacea, is repre- 

 sented in fig. 26. Various other kinds are 

 illustrated in PI. 46. DiefferibacMa Seguina 

 (Araceae) has remarkable lobed granules. 



Here may be mentioned the so-called tannin 

 starch-grains. These resemble ordinary 

 starch-grains, but the cellulose is replaced 

 by tannin, the .granulose being unaltered ; 

 they are coloured blue-black by iron solution, 

 and are found in wood, seeds, &c. 



Starch-granules are usually isolated by 

 slicing the tissues in which they exist, and 

 washing them out. When they are to be 

 observed in situ, either delicate transparent 

 structures (as in the Cryptogamia) must be 

 selected, or sections very carefully made. 

 The cells filled with starch of the potato 

 (PL 46. fig. 20), &c., may be isolated by ma- 

 cerating the structures in water for a day or 

 two. Starch-granules may be preserved for 

 a certain time in glycerine ; but they are, 

 perhaps, best taken fresh from a store of 

 dry granules, when required for examination. 



BIBL. Martin, Phil. Mag. iii. 277 ; Busk, 

 Mic. Tr. i. 58 ; Allinan, Mic. Jn. ii. 163 ; 

 Criiger, Bot. Zeit. xii. 41, Mic. Jn. ii. 173 ; 

 E. Quekett, Ann. N. H. xvii. 193 ; Caspary, 

 Jahrb. wiss. Botanik, i. 448 ; Trecul, Ann. 

 Sc. Nat. 4. x. ; Nageli, Starkekorner fyc. ; and 

 Sitzungsber. bayer. Ak. 1865 ; Sachs, Bot. 

 58 ; Henfrey-Masters, Bot. 



STAURAS'TRUM, Meyen. A genus of 

 Desmidiaceae. 



Char. Cells single, constricted at the 

 middle ; end view angular or circular, with 

 a lobato -radiate margin, or rarely com- 

 pressed with a process at each end. Spo- 

 rangia generally spinous and often globose. 



Many British species. 



S. dejectum (PI. 14. fig. 26). Segments 

 smooth, lunate or elliptical, constricted por- 

 tion very short; end view with inflated 

 awned lobes. Common ; length 1-830". 



8. maraaritaceum (PI. 14. figs. 28, 29). 

 Segments rough, tapering at the constric- 



tion, and with short lateral processes ; end 

 view with five or more short, narrow, ob- 

 tuse rays. Length 1-1176". 



S. gracile (PI. 14. fig. 30). Segments 

 rough, elongated on each side into a slender 

 process terminated by minute spines ; end 

 view biradiate. Length 1-770 to 1-540". 



BIBL. Ralfs, Desmid. 119 ; Rabenht. Alg. 

 iii. 199 ; Archer and Dixon, Qu. Mic. Jn. 

 viii. 77 ; ib. xvii. 103. 



STAURIDIUM, Duj. A genus of 

 Hydroid Zoophytes. 



Char. Stems simple or branched, rooted 

 by a creeping filiform stolon ; polypes 

 borne at the summit of the stems with 

 several whorls of capitate tentacula in the 

 form of a cross. 



S. productum. On marine algae. (Hincks, 

 Hyd. Zooph. 67.) 



STAUROCAR'PUS, Hassall (Stauro- 

 spermum, Kiitz.). A genus of Zygnemaceae 

 (Confervoid Algae), growing in boggy 

 freshwater pools ; distinguished by the re- 

 markable quadrate spore formed in the 

 cross branch produced by conjugation. 

 Hassall enumerates six species. He speaks 

 of, but does not describe or figure, the spores 

 of S. ccerulescens as filled with zoospores. 

 Thwaites, however, saw the spores of S. 

 gracilis resolved into four portions ; and pos- 

 sibly these may become converted into 

 zoospores like the spores of BULBOCHJETE ; 

 or probably they ger- 

 minate directly, as in 

 Spirogyra. 



S. gracillimus. Fila- 

 ments 1-4200" to 

 1-3960" in diam. j 

 spores acutely qua- 

 drangular. 



S.gracilis (fig. 694, 

 and 'PI. 9. fig. 16). 

 Filaments thicker 

 than in the last; 

 spores cruciform. 



S. glutinOSUS. Fila- Conjugating filaments with 

 ments 1-1800" to spores (zygospores). 

 1-1560" in diam. ; blu- Ma S nified ">0 diameters. 



ish green, lubricous; spores four-sided, with 

 the 'angles rounded. 



S. ccerulescens. Filaments about the same 

 size as the last j spores cruciate, with obtuse 

 lobes. 



S. quadratus. Filaments 1-2400" in diam. ; 

 spores between square and globose. 



8. virescens. Filaments 1-3240 to 1-3000" 

 in diam. ; spores cruciate, emarginate. 



BIBL. Hassall, Alg. 176; Kiitzing, Sp. 



Fig. 694. 



Staurocarpus gracilis. 



