CONFERVOIDEJE. 



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CONFERVOIDE^E. 



dimensions and higher organization than 

 any of the preceding ; and indeed they are 

 placed among the lower Fucoids by some 

 authors. They seem to us to be more in 

 place here. They are composed of tubular 

 cells of much larger size than those of any 

 other Confer voids, the entire plant often 

 consisting of one undivided tube, while in 

 other cases the branches arise from true 

 articulations. In Botrydium a very curious 

 structure is exhibited : the plant consists 

 of a tough membranous globule, filled with 

 green matter, rising from a branched, colour- 

 less, root-like portion spreading in the damp 

 ground, the whole consisting only of one 

 very large undivided cell. In Vaucheria 

 and JSryopsis the tubular cell grows into a 

 long filament, more or less branched, but 

 not divided. In Hydrodictyon, which from 

 its general structure appears referable here, 

 the plant is a large net with meshes half" 

 an inch broad, the net itself being com- 

 posed of large tubes rounded at both ends, 

 articulated at the intersections of the meshes. 

 In Codium, the filaments are closely com- 

 bined into a spongy mass. The fructifica- 

 tion of these genera is very varied, so 

 that the group appears scarcely natural ; but 

 the plants are all more or less anomalous, 

 and have affinities with very different tribes, 

 while the comparatively enormous cells of 

 which they are composed are peculiar to 

 them among the filamentous Confervoids. 

 Vaucheria is reproduced by very large oval 

 gonidia covered with innumerable vibratile 

 cilia, by means of which they swim actively 

 in water ; the gonidia are developed from 

 the contents of the ends of the filaments; 

 and zoospores, produced under various cir- 

 cumstances, seem to occur in all the other 

 rnera. In Vaucheria sexual reproduction 

 also known ; sporangial and antheridial 

 branches being formed at the sides of the 

 main filaments. The Saprolegniece (Achlya, 

 &c.), were formerly included in this family, 

 on account of their general structure ; but 

 they are distinguished by the absence of 

 chlorophyll in their cell-contents, and their 

 parasitic habit, which gives them the cha- 

 racter of aquatic Fungi. 



The (Edogoniaceae are green, simple or 

 branched, filamentous plants, attached to fo- 

 reign bodies under water their cells, filled 

 with green matter, presenting a peculiar 

 mode of division ; and the entire contents of 

 the cells are converted into zoospores which 

 have a crown of numerous cilia. In the 

 sexual reproduction, the spores are formed 



from the entire contents of certain cells, 

 which are impregnated by spermatozoida 

 produced on other parts of the plant, or by 

 antheridial plants developed from some of 

 the gonidia. 



The Zygnemaceae are somewhat similar 

 filamentous plants, remarkable for the pro 

 cess of CONJUGATION or inosculation of 

 neighbouring cells of distinct filaments in 

 order to the production of the resting- 

 spores. They are also distinguished by the 

 endochrome being arranged in spiral bands 

 or other patterns on the cell-walls. It is 

 doubtful whether zoospores occur here 

 normally. 



The Confervaceae are simple or branched 

 filamentous forma, of which the essential 

 characters are imperfectly known. They 

 produce numerous zoospores with two or 

 four cilia, in each cell. 



The ChaBtophoraceae differ from the Con- 

 fervacese principally in their habit and mode 

 of branching. They occur in fresh water 

 and in the sea ; and are characterized by the 

 presence of a jelly enveloping the filaments, 

 which form branched, round, or shapeless 

 masses, or flat discoid or irregular plates, 

 and by the cells constituting the joints of 

 the filaments bearing slender bristle-like 

 branches. They are reproduced by zoo- 

 spores, either numerous or solitary in the 

 cells, bearing four cilia; also by spores 

 formed after fecundation. 



The Batrachospermeae exhibit a greater 

 complexity of structure, consisting of jointed 

 moniliform filaments, composed of rows of 

 cells, branched and bearing whorls of ramuli j 

 the filaments of the whorls dense, dichoto- 

 mous, and beaded, some of them growing 

 down over the central filament, and forming 

 a sheath round it. The fructification con- 

 sists of spore-like bodies, or cystocarps with 

 trichogynes, borne on the filaments of the 

 whorls, and of bodies resembling the an- 

 theridia of the Florideae. The plants are 

 brownish green or purplish, and occur in 

 fresh water. 



The Lemaneeaa are freshwater Algae, oc- 

 curring in rapid rivers, attached to stones, 

 by some supposed to bear a close relation to 

 the lower Fucoids. The fronds are branched 

 and of leathery texture, consisting of tubes 

 composed of cellular tissue, the superficial 

 layers small, polygonal, and firmly con- 

 joined the deeper layers, bounding the 

 cavity of the tubes, lax and spherical. The 

 fructification consists of beaded filaments 

 arising from the internal cells, and grow- 



