Class 2. PH^OPHYCE^E (or Fucoidese). 



ALMOST all the Algse of this class are marine and are known as 

 the Brown Seaweeds. They are often termed the Melanophycese. 

 The thallus exhibits great diversity of form ; in some it is a 

 simple filament, in others a flat expansion of cells, and in others it 

 is greatly differentiated. The most highly organized of all seaweeds 

 are members of this class of the brown Algse. The vegetative 

 cells possess one nucleus, and the chromatophores have a distinct 

 brown tinge owing to the presence of phycophcein and phycoxanthw. 

 (the compound pigment being known as phaeophyll). The former 

 can be extracted with water and the latter by means of alcohol. 



Asexual reproduction is by motile cells or zoogonidia. 



Sexual reproduction is either by isogamous or heterogamous 

 gametes, the conjugation of the gametes or the fertilization of the 

 oospheres taking place in all cases outside the plant. The zygospore 

 or the oospore always germinates directly. The motile reproductive 

 cells, whether zoogonidia or gametes, invariably possess two cilia, 

 inserted laterally, and in their movements one cilium is carried in 

 a forward direction and one in a backward direction. 



The class is divided into a number of orders of which only one 

 the Syngeneticcv is freshwater. 



Order I. SYNGENETIC^E. 



The plants included in this order, which is sometimes termed 

 the ' Phasozoosporina?,' are exclusively freshwater. They are Alg* 

 of little note or importance, and may be either solitary or colonial 

 unicells, multicellular, free-swimming or motionless. The cells are 

 often naked, but at other times are surrounded by a mucilaginous 

 cell-wall. In some of the multicellular forms the cells are only 

 loosely held in position by a copious mucilaginous envelope. There 

 is one cell-nucleus and one or more pulsating vacuoles. The 



