CLOSTERimi. 



[ l'^4 ] 



CLOSTERIUM. 



probably variable. Morren states that it 

 becomes a moving gonidium, while most 

 authors state that it becomes a restiug-spore 

 with lirm 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- 

 astrum, described by Caspary and Brauu. 

 (See Pediastrum.) Focke also figures a 

 cov^diiionoiClosterium Lunula, 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 Algse. (See 

 OEbogonium and Spuiogyea.) 



The Cloden'a 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 hj sulphuric acid and iodine 

 (cellulose) ; in its natural condition it often 

 has a reddish tint, especially towards the 

 ends. 



Rabonhorst describes 52 species, with 

 numerous varieties. 



Analysis of ordinary British species : — 



( Cell suddenly narrowed at the ends J at fen uatum, 



1, ' into a conical point \ 1.1-57". 



I Cell not suddenly narrowed 2 



"Cell striated, tapering into a beak 

 at ends, lower margin prominent 



at middle 3 



Cell very minute, beaked, straight, i Griffilkii*, 

 "[ not striated, nor lower margin - 1. l-oOO to 



prominent at middle ( l-4oU". 



I Cell not beaked ; if striated, lower 

 L margin not prominent at middle 6 



i Beaks setaceous, as long as or lon- 

 ger than body 4 

 Beaks linear, much shorter than 



( Beaks much longer than body |j ^.n^jir 



\ Beaks about as long as body 



( ros/ra/um, 

 •")!. 1-169". 

 C Cells much inflated at middle, j lialfsii, ^^ 



I rapidlv tapering at ends ( 1.1-79". 



1 Cells slightly inllated at middle, ( Jinealuin, 

 I gradually tapering at ends ^ 1.1-48". 



7. 



10. 



11. 



12 



13. 



( 



14 



15, 



* PI. II. figs. 57 & 58. 



t 1*1. 14. figs. 45 & 4t> (Conjugation). 



^Cell minute, acicular; sporangium 



; cruciform 7 



J Cell not acicular ; sijorangium or- 

 V. bicular 8 



(Ends obtuse < j yl\iQii 



1 T-, , , i acutum, 



f iinds acute •< j^ 1-177" 



/Cell semilunate or semilanceolate, 

 I lower margin inclined upwards 



-( at ends 9 



Cell with either truncate ends, or 

 lower margin inclined down- 

 wards at ends 12 



J Vesicles numerous, scattered •< , itjo" 



( Vesicles in a longitudinal row 10 



J Ends of cell slightly curved up- i tiirgidum, 

 J wards ; longituoiual strise distinct ( 1.1-39". 

 "i Ends of cell straight; striae none 



V or indistinct 11 



I Cell linear-lanceolate ; ends coni- j aeerosum t, 



; cal, obtuse 1 1. 1-70 to 1-58". 



) Cell semilanceolate; ends auh- \ lanceolatum, 



y. acute I 1.1-64". 



i Cell not striated, crescent-shaped 13 



^ Cell either not crescent-shaped, or 



I else distinctly striated 17 



j" Vesicles numerous, scattered -5 I'^l'.tiS'^"' 



^ Vesiclesin longitudinal row 14 



' Empty cell colourless, ends round- 



ed.. 15 



Empty cell usually reddish, ends 

 subacate 16 



! Lower margin of cell inflated at j moniliJerumX, 

 middle 1 1. 1-70 to 1-60". 

 Cell not inflated at midtUe < *" " -')so" 



(Cell inflated at middle l 1 T-9U to 1-60". 



( Cell slender, notinflated at middle^ "^r'l^l^O" 

 / Lower margin of cell inclined up- j ^ij /,^^^ ^ 

 wards at truncate ends; longitu- J 1 i.h-'' 

 dinal striae none or indistinct ... [ ' " '' • 

 Ends of cell inclined downwards ; 



stria" distinct 18 



I Longitudinal striso to 7,prominent 19 

 ( Longitudinal stri« numerous, fine 20 



rCell semiluna or crescent-shaped -j '^"^ " "75'" 



"( i angiistuhim, 



(Celllmear -^ j. i.^q". 



(Cell narrowly linear, nearly Sjiineidion, 



) straight :. n-69 to 1-111". 



I Cell tapering, curved 21 



.'Longitudinal stria; crowded, 8U- * s/ri'oZn/iini, 



j turcslto3.. ■) 1.1-80 to 1-68". 



■^ Longitudinal striae not crowded ( intermedium, 

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



BiBL. Meneghini, Syn. Desmid.,Linncpa, 

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

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

 Brebisson, Ahf. Fidaise, e^'- Conjiujaice ; Kiit- 

 zing, Spec. A/c/. 16:^.; iiei]ie\e\, Ann. N. H. 

 2 ser. xiii. 25G ; Braun, licjuv. (Bay Soc. 

 1853, 280, 292) ; Morren, Ann. Sc. Nat. 

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

 Osborne, Qu. Mic. Jn. iii. 54; Ileufrey, 



» PI. 14. fig. 40. 



t PI. 11. figs. 41 & 42 (Conjugation), 

 t PI. 14. fig. 43. 

 ^ PI. 14. fig. 44. 



16. J 



17. 



18. 



19 



20, 



21 



