SUB-CLASS I 



PH^OPHYCE^E 



WITH the exception of some of the species of 

 Lithoderma and the genus Pleurocladia, represented 

 only by a minute form of doubtful affinity dis- 

 covered by Alexander Braun in the Tegeler See 

 near Berlin, all the Phceophycece, or Melanophycece as 

 they are otherwise called, are seaweeds. They 

 agree in the fact that all their motile reproductive 

 cells, zoospores, antherozoids, and gametes are pro- 

 vided with two lateral cilia, one pointed forwards 

 and the other backwards in motion ; in the fertilisa- 

 tion of their oospheres and the conjugation of gametes 

 outside the parent plant, and the direct germination 

 of the zygote which is the product of this union ; 

 in the possession of brown chromatophores tinged 

 with phycophaeine and phycoxanthine (the phyco- 

 phaeine being soluble in water and the phyco- 

 xanthine in alcohol, the compound pigment being 

 termed phaeophyll); and in having mostly but one 

 nucleus in the vegetative cells. The vegetative 

 body of the plants coming under this sub-class is 

 of great diversity, including the most highly 

 organised of all seaweeds, of giant dimensions and 



