198 



ALG.E 



A true understanding of the sometimes complicated process of sexual 

 reproduction in the Florideag has been much obscured by the numerous 

 terms employed by the older writers for identical organs, and by incor- 

 rect notions as to their functions. The true sexual organs, antherids 

 and proca?'ps, are nearly always formed on individuals which do not 

 produce tetraspores ; and the sexual individuals may be monoecious or 

 dioecious ; the latter is the most common condition. If the Ulvaceae 

 are rightly included under Floridese, we have here a wide departure from 



Fig. 175. — Stages in the development of the reproductive organs of Nentalion injiltifiduin Ag. 



(magnified). (Speniiat. — pollinoids.) 



the normal type, sexual reproduction taking place by the conjugation of 

 motile swarm -cells. 



The a?itherid consists, in its simplest form (Porphyraceae), of a soli- 

 tary cell at the end of a long segmented branch ; and in this case it 

 gives birth to a single pollinoid ; in other forms the antheridial cells 

 occupy a similar position to the tetraspores, being formed in groups at 

 the expense of the ultimate branchlets. They are also sometimes pro- 



