213 



■ ALGJL 



some other genera is very soft and gelatinous ; the whole iS usually' 

 enclosed in a gelatinous envelope. The tha-llus is of filamentous stru<<^ 



ture, and either simple or branched, the 

 secondary axes often arranged in whorls^ 

 The main axis usually consists of a central 

 row of cylindrical cells surrounded by a 

 pseudo-cortex composed of smaller . ^cells, 

 either placed in rows at right angles to 

 the axis, or parallel to it. It may, how- 

 ever, consist of a single uncorticated row 

 of cells. Batrachospermum is a; genus of 

 small green fresh-water Algae of great beauty 

 from the symmetry of their branching. The 

 stem grows by means of a cup-shaped 



Fic. i%<j.—Batrachosp'^rmum monilifortne Roth, a, portion of plant (x 30); /;, portion witlu . 

 cystocarps, cccc(x 150). (From nature and after Cooke.) ' ' 



