CONFERVACE^E, 



[ 197 ] 



CONFERVOIDE^E. 



entangled filaments twice as thick, deep 

 glossy green, and many feet long. 



The cell-walls of these large marine 

 species present a curious striated appear- 

 ance when treated with acids, which led 

 J. Agardh, apparently erroneously, to sup- 

 pose they are composed of spiral filaments. 

 (See SPIRAL STRUCTURES.) 



BIBL. Harvey, Pliyc. Brit, j Thuret, loc. 

 cit. j Kiitzing, Sp. Alg. ; Hassall, Freshw. 

 Alg. 213 ; Braun, Rejuv. (Ray Soc. 1853, 

 184) ; Rabenhorst, Fl. Alg. iii. 322. 



CONFERVA'CEJE. A family of Con- 

 fer voidese. Marine or freshwater Algae ; 

 composed of articulated filaments, simple 

 or branched ; cells cylindrical, shortish, not 

 conjugating. The fourth and fifth genera 

 given below are placed here doubtfully; 

 Stigeodonium, if a good genus, leads to 

 Draparnaldia among the Chaetophoraceae. 

 Reproduction by zoospores; spores un- 

 known. 



Synopsis of the British Genera. 



Conferva, Filaments unbranched. Zoo- 

 spores minute, numerous in the cells. Sea, 

 brackish, and fresh water. 



Glceotila, Microspora, Chcstomorpha, Cla- 

 dophora. Filaments tufted, much branched. 

 Sea and fresh water. Zoospores minute, 

 many in a cell. 



Rhizoclonium. Filaments decumbent, 

 with small lateral rootlike branches. Zoo- 

 spores minute, numerous. Sea, brackish, 

 and fresh water. 



Ulothrix. Filaments simple, often fasci- 

 culated, joints short. Zoospores 4-ciliated; 

 two, four, or more in a cell. Fresh water. 



Stigeoclonium. Filaments branched, form- 

 ing tufts, the ramules running out into 

 slender points ; cell-walls often dissolving 

 to emit the zoospores. Zoospores 4-ciliated, 

 one in a cell. 



CONFERVOI'DE^E or CHLOROSPO'- 

 RE^E. An order of Algae. The Chloro- 

 spores or Confervoids, the lowest order of 

 the Algae, display a preponderating number 

 of truly microscopical plants, and constitute 

 one of the favourite and most instructive 

 fields of microscopic research. As yet, how- 

 ever, the minute history of development is 

 wanting in a very large number, while the 

 facts already disclosed are so varied that it 

 becomes a matter of difficulty to draw up a 

 sketch of their characteristics in a brief 

 space. 



Among the Palmellaceae we find some of 

 the simplest forms of vegetable life, where 



the organization is reduced to the condition 

 of a single microscopic membranous vesicle 

 enclosing nitrogenous contents, ordinarily 

 tinged with chlorophyll, and containing 

 starch. Such we have in Protococcus, which 

 in its various forms appears as a green or red 

 stain on damp surfaces, or a green or red 

 scum in water. These plants multiply by 

 the subdivision of the cells into two or four 

 new ones, which separate and repeat the 

 process. In addition to the vegetative 



Ewth by subdivision, going on in damp air 

 s cells being held together more or less 

 ily in a gelatinous crust), the contents 

 of the individual cells are set free by solution 

 of the membranes when placed in water, 

 and emerge as ciliated zoospores, endowed 

 with active motion. Advancing a step, we 

 come to a number of genera not yet well 

 defined, in which the membranes of the 

 parent cells soften into a land of gelatine, 

 during the process of subdivision, and hold 

 the new cells together in groups of definite 

 or indefinite form; among these are Palmella 

 Gloeocapsa, and others of like nature, in 

 which at present no zoospores have been 

 discovered. In Coccochloris a process of 

 conjugation occurs. These genera exhibit 

 a ?'estingform, characterized by the increased 

 thickness of the membrane of the cell, and 

 a change of the green contents into a 

 brownish, reddish, or even crimson colour. 

 With the Palmellaceae we shall associate 

 a number of Unicellular Algae, whose cha- 

 racters and affinities are still obscure. 



The Ulvaceae are not widely separated 

 from the Palmellaceae ; but the conjunction 

 of the cells into a definite membrane, indi- 

 cates a higher organization. In other re- 

 spects, however, they hardly differ more from 

 some of the more perfect genera of Palmel- 

 laceae, than those do from Protococcus ; and 

 therefore, although more conspicuous and 

 extensively developed than the Nostochaceae 

 and Desmidiaceae, it seems natural to place 

 the Ulvaceae near the Palmellaceae, espe- 

 cially as the reproduction by cell-division 

 and by zoospores is analogous in all respects 

 to what is seen in Protococcus, of which they 

 would appear to be the permanently aquatic 

 representatives. Prasiola and Schizogonium, 

 however, differ from the other Ulvaceae in 

 the absence of zoospores, the homogeneous 

 not granular contents of the cells being dis- 

 charged as motionless spore-like bodies, 

 from which new fronds grow up. 



The Nostochaceae exhibit but a slight 

 advance in organization over the Palmel- 



