i r. i:s ii \\ AT i: it ALG.E OF THE UNITED STATES. 



escaped iiiti) tin- water, through tin- cell wall. Each cell in this way gave origin 

 to a single /.ooNpore. The walls did not nu It away in the water, and, as a nuinlicr 

 of conse< utivc cells underwent these changes at the same time, the filament or a 

 portion of it was left as an empty shell. The zoospores were of the usual shape, 

 witli a bright anterior spot or beak. The number of cilia was not noted. After 

 a time they settled down generally in clusters, attaching themselves to some foreign 

 particle, dropping their cilia and acquiring a cellulose wall. (Fig. 1 e, pi. 18.) They 

 then elongated, underwent the ordinary cell division in a transverse direction, and, 

 by the repetition of this, gradually grew into filaments similar to that from which 

 they sprang. 



1 ii,'. "i '/. pi Itf, represents a young filament just formed in this manner, magni- 

 fied 500 diameters. 



Genus CLADOPHORA, KTZ. (1843.) 



Fila ri.'llularuin serie siuiplici formats, rarie ramosa. Rami Clo ccntrali similes. Cytioderma 

 jilt Tiini.|u.- crusbum, lamellosum. Cytioplasma parietale. 



Filaments r< imposed of a simple series of cells and variously branched. Cytiodcrni mostly thick 

 and hum-Hull-- Cytioplasni parietal. 



Remark*. The Cladophora are branched plants of rather rigid habits, which 

 gmsv both in salt and fresh water. They are readily recognizable by their 

 comparatively still appearance, the absence of gelatinous matter about them, and 

 by the want of regularity in their branching. A large number of species have 

 been described, most of which are marine. They are exceedingly difficult to define, 

 and it is very jxissible that their hitherto undiscovered sexual reproduction maybe 

 finally found to afford the only true characters. I have identified two European 

 forms as growing near this city, and a third has been recognized by Prof. Harvey, 

 as found in our northern States. 



I have never seen the production of zoospores in this family, but they are said 

 to be formed by the simultaneous division of the layer of chlorophyllous proto- 

 plasm, which fills the outer part of the cell cavity. They exhibit the power of 

 \i iy active motion even before their exit from the cell, which occurs through a 

 papilloid orifice, mostly at the end of the cell, sometimes in its side. Their cilia 

 are sometimes two, sometimes four in number, and their life-history appears to be 

 precisely similar to that of other zoosporcs. 



1. glomerata, (LINN.) 



Kamuli till primarii in parte saperiore atque ramornm ordinis second! et tcrtii plerumque 

 fasciculate- Tel penicilliformi-aggregati. Cellulte maxima; vegetse cytioplasmate cellularum 

 parieti retifonni- vol snbspiraliter applicato. Cellulae fructiferse semper terminates, inferiores 

 semper steriles videntur. (R.) 



Syn. Cl. glomerata, (KOrziNG) RABENHORST, Flora Europ. Algarnm, Sect. III. p. 337. 



Hob. Lake Ontario; Pickering. Falls of Niagara; Lakes Erie, Huron, and Michigan; 

 Fourth Lake, near Madison, Wisconsin ; Bailey. 



" Filaments tufted, bushy, somewhat rigid, much branched, bright grass-green ; branches 

 crowded, irregular, erecto-patent, repeatedly divided ; ultimate ramuli secund, subfasciculate ; 

 articulations 4-8 times ns long as broad." 



