CLOSTERIUM. 



[ 184 ] 



CLOSTERIUM. 



probably variable. Morren states that it 

 becomes a moving gonidium, while most 

 authors state that it becomes a resting-spore 

 with firm membranous coats. Again, Mor- 

 ren assumes the segmentation of the green 

 contents of this spore or gonidium into a 

 number of portions, each of which becomes 

 a perfect individual. Focke gives a figure 

 which seems to bear out this statement ; 

 and it would find an analogy in the mode 

 of reproduction by active gonidia in Pedi- 

 astrwn, described by Caspary and Brauu. 

 (See PEDIASTRUM.) Focke also figures a 

 condition of Closterium Lunida, in which the 

 whole of the green contents of an individual 

 cell had become retracted from the walls, 

 and converted into a number of green glo- 

 bular bodies, with proper coats, resembling 

 the resting spores found under certain con- 

 ditions in many filamentous Algoe. (See 

 (EDOGONIUM and SPIROGYRA.) 



The Closteria are capable of fixing them- 

 selves by one extremity to foreign bodies, 

 and Ehrenberg asserted the existence of a 

 foot-like organ ; but no such structure seems 

 to exist. The individuals also possess a 

 power of moving in water, but the nature 

 of this is inexplicable at present. The seg- 

 ments of the outer membrane separate from 

 each other when their contents decay, and 

 often when they are dried. The membrane is 

 coloured blue by sulphuric acid and iodine 

 (cellulose) ; in its natural condition it often 

 has a reddish tint, especially towards the 

 ends. 



Rabenhorst describes 52 species, with 

 numerous varieties. 



Analysis of ordinary British species : 



i Cell suddenly narrowed at the ends j attenuatum, 

 1. < into a conical point .................. ( 1.1-57". 



( Cell not suddenly narrowed ......... 2 



'"Cell striated, tapering into a beak 

 at ends, lower margin prominent 

 atmiddle .............................. 3 



2 i Cell very minute, beaked, straight, (Grifflthii*, 

 "' not striated, nor lower margin } 1. 1-3 00 to 

 prominent at middle ............... ( 1-450". 



Cell not beaked ; if striated, lower 



margin not prominent at middle 6 

 I Beaks setaceous, as long as or lon- 

 o ) ger than body ........................ 4 



' } Beaks linear, much shorter than 

 ( body 



< Beaks much longer than body ...... { 



( Beaks about as long as body ...... -| f^? 



Cells much inflated at middle, j Xalfsii, 

 rapidly tapering at ends ............ ( 1.1-79". 



Cells slightly inflated at middle, j lineatum, 

 gradually tapering at ends ...... \ 1.1-48". 



* PI. 14. figs. 57 & 58. 



t PI. 14. flga. 45 & 46 (Conjugation). 



{Cell minute, acicular; sporangium 

 cruciform 1 

 Cell not acicular; sporangium or- 

 bicular 8 



, (End. obtuse JT&HO-. 



I Ends acute JTwjJ". 



/Cell semilunate or semilanceolate, 

 lower margin inclined upwards 



8.^ at ends 9 



Cell with either truncate ends, or 

 lower margin inclined down- 

 * wards at ends 12 



9 J Vesicles numerous, scattered -J 



' Vesicles in a longitudinal row 



C Cell linear-lanceolate ; ends coni- ( acerosum t, 

 HJ cal, obtuse ..................... ... ...... \ 1. 1-70 to 1-58". 



} Cell semilanceolate ; ends sub- j l-anceolalwn, 



; acute .................................... f 1.1-64". 



j Cell not striated, crescent-shaped 13 

 12- < Cell either not crescent-shaped, or 



( else distinctly striated ............ 17 



j" Vesicles numerous, scattered ...... \ E \ re ^ b ^? ii ' 



13.^ Vesicles in longitudinal row ......... 14 



(^ Empty cell colourless, endsround- 



14. Empty cell usually reddish, ends 



subacate ................................. 16 



( Lower margin of cell inflated at ( moniliferuml, 

 15 J middle .................................... } 1. 1-75 to 1-60". 



Cell not inflated at middle 



> ............... 



^Cell slender, not inflated at middle] 



/Lower margin of cell inclined up- i ,. j 



wards at truncate ends ; lougitu- ) d ^ymotoc um , 

 17.-J dinal striae none or indistinct ... | L L " 6& 



Ends of cell inclined downwards ; 

 { striae distinct ........................... i& 



, ( Longitudinal stria? 3 to 7,prominent 19 

 ( Longitudinal striae numerous, fine 20 



lit. 



i Cell semiluna or crescent-shaped -j coi um> 



1. 1-75". 



I Cell linear , 



(Cell narrowly linear, nearly (juncidum, 



20. > straight { 1-69 to 1-111". 



( Cell tapering, curved 21 



/Longitudinal striae crowded, su- j striolatum, 



2 . ! tureslto3 \ 1. 1-80 to 1-68". 



j Longitudinal striae not crowded I intermedium, 

 (. sutures usually more than 3 ( 1. 1-77 to 1-54". 



BIBL. Meneghini, Syn. Desmid.,Linna>a f 

 xiv. 201 j Ehrenb. Infus. ; Ralfs, Brit. 

 Desmidiece ; Smith, Ann. N. H. 1850, v. 1 ; 

 Brebisson, Alg. Falaise, fy Conjugates ; Kiit- 

 zing, Spec. Alg. 163 ; Berkeley, Ann. N. H. 

 2 ser. xiii. 256; Braun, Itejuv. (Ray Soc. 

 1853, 289, 292) ; Morren, 'Ann. Sc. Nat. 

 2 s<r. v. 257 ; Focke, Physiol. Stud. 1847 ; 

 Osborne, Qu. Hie. Jn. iii. 54 ; Henfrey, 



* PL 14. fig. 40. 



t PI. 14. figs. 41 & 42 (Conjugation). 



I PI. 14. fig. 43. 



$ PI. 14. fig. 44. 



