SPIRAL STRUCTURES. [ 714 ] 



SPIRILLUM. 



says he has likewise detected an analogous 

 spiral-fibrous structure in the primary cell- 

 wall of the structures of the Phanerogamia. 

 The delicate striation of the membranes of 

 the Confervas and slightly thickened liber- 

 or parenchyma-cells of many Flowering 

 plants form a desirable object of investiga- 

 tion for those accustomed to the delicate 

 observation of the markings of the valves of 

 the Diatomaceae. The use of reagents, 

 such as nitric acid and solution of potash, 

 boiling, maceration, and other means must 

 be employed for this purpose, controlled 

 always by a careful observation of the 

 structures in their natural state and in diffe- 

 rent stages of development. It is not im- 

 possible that all secondary deposits may 

 prove, as Meyen assumed, to have a fibrous 

 constitution, and true membrane to be con- 

 fined to the primary walls. One set of 

 layers, however, seems always to resist the 

 endeavour to resolve them into fibrils, 

 namely those of the horny and fleshy AL- 

 BUMEN of seeds. 



As to the mode of the formation of spiral 

 secondary deposits, little is certainly known. 

 Criiger attributes them to spiral circulation 

 of the secreting protoplasm over the cell- 

 wall in the position of the future fibres ; 

 but this is a somewhat speculative notion. 

 Others have asserted that they are formed 

 by gradual collocation of visible granules ; 

 this is certainly an error. We have observed 

 the gradual formation of the spiral band 

 in the elater of Marchantia, where it is at 

 first a faint spiral trace with indistinct 

 edges ; as it grows thicker, the edges become 

 more and more defined ; and it is produced 

 originally in the exact position and pattern 

 which it subsequently retains. 



The actively moving spiral filaments or 

 SPERMATOZOIDS of the Ferns, Mosses, Cha- 

 racese, &c. have nothing in common, ex- 

 cept the spiral form, with the structures de- 

 scribed in this article ; they belong to the 

 protoplasmic structures or cell-contents, as 

 is also the case with the spirally-arranged 

 green contents of SPIROGYRA ; while this 

 article refers exclusively to cellulose struc- 

 tures belonging to the cell-wall. 



See also CELL, Vegetable; SECONDARY 

 DEPOSITS ; PITTED STRUCTURES ; and TIS- 

 SUES, Vegetable. 



BIBL. General works on Vegetable Ana- 

 tomy ; Schleiden, Ann. N. H. vi. 35, 1839 ; 

 E. Quekett, Tr. Mic. Soc. i. 1 ; Ann. N. H. 

 xv. 495 ; Mohl, Verm, Schrift. 285, Ann. Sc. 

 Nat. 2. xvi. 242; Veg. Cell, 14; Agardh, 



Cell. Vegetal. 1852 ; Criiger, Sot. Zeit. xii. 

 57, 833, xiii. 601 ; Caspary, Sot. Zeit. xi. 

 801; Tre"cul, Ann. Sc. Nat. 4. ii. 273; 

 Schacht, Pflanzenzelle, 1852 ; Sot. Zeit. viii. 

 697 ; Unger, Linncea, xv. 385 ; Spencer, 

 Linn. Tr. xxv. 405 ; Hofmeister, Handb. Sot. 

 i. ; Sachs, Sot. 22. 



SPIRILLI'NA, Ehr. A doubtful genus 

 of marine Infusoria, of the family Arcellina. 



Char. Shell siliceous, porous, forming a 

 flat spiral. S. vivipara. Shell microscopic, 

 hyaline, smooth, containing numerous em- 

 bryo shells. Found in America. (Ehren- 

 berg, Abh. Berl. Ak. 1841, 402, 422.) 



SPIRILLI'NA, Ehr., Rupt. Jones. A 

 genus of Rotaline Foraminifera, near Pulvi- 

 milina. 



Char. Shell hyaline, consisting of a single 

 elongated chamber, coiled into a flat close 

 spiral ; orifice simple, as wide as the tube. 



Two recent British species, S.perforata 

 (PI. 24. fig. 5), and margaritifera ; also some 

 fossil (Jurassic and Tertiary). 



BIBL. Williamson, Rec. For. 91; Car- 

 penter, For. 180 ; Parker and Jones, Ann. 

 ^#.4.^.386; ix. 221. 



SPIRIL'LUM, Ehr. A genus of Schizo- 

 mycetous Fungi. 



"Char. Consisting of a colourless, tortuous 

 or cylindrical spiral filament. 



These very minute organisms, found in 

 infusions and decomposing liquids, are very 

 interesting objects on account of the re- 

 markable character of their corkscrew-like 

 movements. They multiply by transverse 

 division, separating into two portions while 

 in motion. They are jointed or septate, but 

 the joints are not alwavs easy of detection. 

 They are insoluble in boiling potash. Their 

 structure is best examined when they are 

 preserved in a dry state. They are appa- 

 rently related to the Oscillatoriaceous Algae, 

 but are very different from Spirulina, with 

 which they have been compared. Spiril- 

 lum bryozoon consists of the spermatozoids 

 of Mosses. 



Like the other Schizomycetes, they pro- 

 duce decomposition in organic liquids. A 

 species of Spirocliceta is supposed to be the 

 cause of relapsing fever, and occurs also in 

 certain purulent discharges. 



8. tenue (PI. 7. fig. 17/). > Filament 

 slightly tortuous, indistinctly jointed ; spiral 

 of three or four turns ; movement active ; 

 length 1-1000" ; diam. 1-12,000". 



8. undula (PI. 17. fig. 17 g). Filament 

 very tortuous, jointed; spiral of one or one 

 and a half turns ; length 1-1500" ; diam. 



