ASTASI.EA. 



liform filament single, arisinp- suddenly from 

 the anterior part of the body, or from a 

 more or less deep notch in it ; oral aperture 

 very extensile {Kent), leading to a long 

 oesophagus. 



Dujardin forms an unnecessary genus, 

 Peranema, to contain those species in 

 which the filament arises from tlie gradu- 

 ally narrowed anterior extremity of the 

 body. 



A. hcematodes, E. (PI. 30. fig. 16). Fu- 

 siform, tail very short ; at fii'st green, then 

 red ; length 1-380". 



The flagelliform filament was absent in the 

 specimens represented in the figure. The 

 substance of the body was insoluble in cau- 

 stic potash, even when heated to boiling, 

 merely becoming swollen. It exhibited nu- 

 merous vacuoles, which in some of the or- 

 ganisms were filled with green grains of 

 chlorophyll. The colour arose from di- 

 stinct granules of pigment, scattered through 

 the colourless substance; when treated with 

 solution of iodine and then sulphm'ic acid, 

 the AsiasicB became spherical, and were co- 

 loured blue, bluish green, and purplish blue, 

 the purple tint apparently indicating the 

 presence of cellulose. It was, however, 

 afterwards found that these colours were 

 produced by the acid alone. 



This curious organism colours the water 

 of ponds &c. blood- red. 



A. Ihrnnda, D. (PI. 30. fig. 17). Fusi- 

 form, colourless ; length 1-550". 



There are other species ; but they are ill- 

 defined. A. 7iivalis, Shuttleworth, found in 

 red snow, would appear to be an active form 

 of Protococcits nivalis. 



BiBL. See Astasi^a; also Shuttleworth, 

 Pibl. de Geneve, Feb. 1840; Kent, Infus. 

 p. 375. 



ASTASI^'A, Ehr.— A family of Flagel- 

 late Infusoria. 



Char. Body of spontaneously variable 

 form, mostly with one or more flagelliform 

 filaments. Insoluble in solution of caustic 

 potash. 



This family corresponds nearly to the Eu- 

 glenia of Dujardin, who asserts the existence 

 of a contractile integument. Foi-m of the 

 body variable, sometimes becoming sphe- 

 rical, at others cylindrical, fusiform, &c., 

 and exhibiting a head or tail-like process, 

 or both. The Astasipea are distinguished 

 from the Amcebeea by the absence of the 

 irregular processes sent out by the latter 

 from all parts of the body ; and'by the pre- 

 sence of a distinct moutli. 



[ 83 ] ASTERIGERINA. 



The forms included under the family thus 

 characterized are still very imperfectly un- 

 derstood ; and it is probable that some of 

 them, separated generically by Ehrenberg, 

 are only transitional condirions of others. 

 Infusoria exactly resembling Astasia hcema- 

 todes and Euglena viridis occur without the 

 flagelliform filament ; Euglena also occurs in 

 a resting form, surrounded by a gelatinous 

 envelope, like Chla})iido7Honas,iind undergoes 

 division into 4, 8, IG or more new indivi- 

 duals in this state, so as to form irregular, 

 floatmg Algoid patches. The gi-een bodies 

 make their escape from the gelatinous enve- 

 lopes under certain circumstances, just in 

 the same way as the zoospores escape from 

 the cells of the Confervoid Algae. This 

 resting form also exhibits another character, 

 especially in winter; the gelatinous envelope 

 acquires a firm, dense, membranous coat over 

 its periphery, like the resting spores of the 

 Confervoids, and in some cases this coat is 

 polygonal and marked with ridges &c. It 

 is probable that the colour of the species is 

 not constant, since it seems to depend upon 

 similar substances to that of the PalmeUacese, 

 which are known positively to change from 

 green to red, and vice versa, and even to fade 

 into an almost colourless state when kept in 

 the dark. These organisms stillrequire much 

 careful examination, not of isolated speci- 

 mens, but by watching their developmental 

 history constantly for extended periods and 

 through different seasons. More is said on 

 this subject under PEOTOCOCCrs. 



The following Table gives the genera of 

 Ehrenberg and Dujardin : — 



Attached CofactuTO, Ehr. 



Unattached. 



Two eye-spots DMigma, 'Ehr. 



One flagelliform filament. 

 One eve-spot. 



With a tail-like process Euglena, Ehr. 



Without „ Amblyoyhis.'Ehi. 



Ko eve-spot j ^s/a«a, Ehr. (& 



IVo flagelliform filaments. 

 Both alike. 

 Animals green, with a red 



eye-spot ChIoroqonimn,'E. 



Colourless, no eye-spot Zygoseimis,D\x]. 



One anterior, the other trailing 



and retractile Heteroiienxa.Jiw]. 



Several filaments Polyselmis, Duj. 



BiBL. Ehrenberg, J??/. ; Dujardin, Infus.; 

 Morren, Pxibefact. d. Eaux, Brux. 1841 ; 

 Cohn, Protococ. plitv., Nova Acta Ac. L. C 

 N. C. xxii. p. 397. (Abstr. Rarj Soc, Bot. 

 1853, p. 352.) 



ASTATIIE. See Primobdial Utricle. 



ASTEPJGERI'XA, D'Orb.— A pseudo- 

 genus of Foraminifera, comprising species 



G 2 



