32 



Female Thallus. The structure of the female thallus is 

 similar to that of the male thallus with the exception that 

 the conceptacles contain numerous oogonia or female repro- 

 ductive organs which have eight non-ciliated and non-motile 

 oospheres or female cells. The oospheres are forced from the 

 conceptacle into the sea water where fertilization takes place 

 outside of the plant. The zygotes develop by repeated cell 

 division into a male and a female thallus. 



In some species of brown alga the thallus is monoecious 

 bearing conceptacles with antheridia and others with oogonia. 

 The laminarias or species of brown algse grow to a great 

 length. In all forms the vegetative plant is highly developed. 



RED ALG^E 



The thallus of the red algae while large in some species 

 is usually much smaller than the typical brown algae and is 

 more finely dissected. Some forms have almost hair-like 

 divisions. The thallus contains chlorophyll but its green 

 color is masked by the red pigment or Phyccerythrin which 

 is present. Red algse occur in deep water, the phycoeryth- 

 rin is supposed to assist the assimilation process. Many of 

 the red algse are characterized by being soluble in fresh 

 water. Irish moss, a well known drug, is completely soluble 

 in 30 parts of water. It is edible and nutritious as are other 

 forms of red algse. Reproduction is rather complicated in 

 the forms in which it has been worked out. In a typical 

 case the antheridia are unicellular and are borne at the ends 

 of short branches. Each antheridium develops a single 

 binucleated non-motile sperm. The female sex organ or 

 procarp consists of a carpogonium and trichogyne associated, 

 in some forms, with other cells. The carpogonium contains 

 the egg cell and there is no cell wall separating it from the 



