104 



Chlorophycece 



Toni] which possesses filaments 10 37 /* in diameter and segments 2 5 times 

 longer than the diameter (fig. 39 A). The common form of this species pos- 

 sesses no branches whatever 

 and occurs abundantly in ponds, 

 ditches, drains, streams and 

 cataracts all over the country, 

 thriving well in water in which 

 considerable putrefaction is 

 taking place. The following 

 varieties of it are widely distri- 

 buted : var. Kochianum(Kutz. ) 

 Stockm. [=R.KochianumKi\tz.; 

 R. flavicans Rabenh.], var. tor- 

 tuosum (Kiitz.) Stockm. (fig. 

 39 B E), and var. riparium 

 (Harvey) Stockm. 



Genus Cladophora 

 Ktitz., 1843. This is the 

 best known genus of the 

 family and is widely dis- 

 tributed in salt and fresh 

 waters. The thallus is 

 branched, the type of 

 branching varying with 

 different species, and the 

 segments are 6 12 (or 

 even up to 20) times longer than their diameter. There are usually 

 many nuclei in a segment, but they may be reduced to two or even 

 one. The chloroplast is parietal and most commonly reticulate, but 

 all intermediate stages are met with between an elongated reticu- 

 late cylinder and isolated plates 1 . There is one pyrenoid in each 

 isolated plate or in each corresponding piece of the reticulum. 

 The cell-wall consists of an inner and outer layer, and, according 

 to Brand, of an 'outermost' layer which can be separated by acetic 

 acid. The zoogonidia are very numerous and escape from the 

 mother-cell through an opening formed by a complete absorption 

 of the cell-wall. Nordhausen 2 regards the basal branching of the 

 segments in a filament of Cladophora as a peculiar process, to 

 which there is nothing strictly comparable in other Algae. Brand 

 states that the species with strong, primary, basal organs of attach- 



Fig. 39. A, Rhizoclonium hieroglyphicum 

 Kiitz., single cell showing chloroplast and 

 pyrenoids, from Sheep's Green, Cambridge 

 (x500). B E, E. hieroglyphicum Kiitz. var. 

 tortuosum (Kiitz.) Stockm., from Heaton, 

 W. Yorks.; B and C, x 100; D and E, x 500. 



1 Brand in Beitr. z. Bot. Centralbl. x, 1901. 



2 Nordhausen in Pringsheim's Jahrb. f. wiss. Bot. xxxv, 1900. 



