Class 1. RHODOPHYCE^; (or Floridese). 



THIS class comprises the Algae usually known as the Red 

 Seaweeds. They exhibit a variety of colours from bright red and 

 purple to dark brownish-reds, brownish-green, blue-green and 

 black. Very few of the genera are freshwater forms. 



The thallus is multicellular, very diverse in form, and consists 

 of simple or branched cell-filaments which may be merely held in 

 close proximity by mucilaginous material, or bound together by a 

 tough intercellular substance, giving the thallus a parenchymatous 

 appearance. The branching of the cell-filaments is very varied, 

 the plants exhibiting many types of branching. The filaments 

 increase in length by the repeated divisions of an apical cell. 

 The cells are all protoplasmically continuous through pits in the 

 transverse or cross-walls of the filaments. Each cell may contain 

 one well differentiated nucleus, or more rarely the thallus may 

 consist largely of coenocytes. The chromatophores are distinct 

 and the chlorophyll is masked by either a red colouring-matter 

 phycoerythrin, or a blue colouring-matter phycocyanin. Some- 

 times pyrenoids are present. 



Asexual reproduction takes place by motionless spores known 

 as tetraspores (or tetragonidia), which are generally bright red, 

 and have neither cilia nor cell-wall. They are produced in a 

 tetrasporangium (or tetragonidangium), usually in variously ar- 

 ranged groups of four. This is the most common form of repro- 

 duction. Zoogonidia are absent from the entire class. 



Sexual reproduction by male and female cells is wanting in 

 some, but present in others. The female organ is a procarp 

 which consists of a single cell containing a cell-nucleus, the 

 carpogonium, drawn out into an attenuated, hair-like process called 

 the trichogyne. The latter is homologous with the receptive spot 



