Fig. 88 Notheia anomala. A, plant growing out from Hormosira. 

 Bj point of entrance of parasite into host ( x 40). C, conceptacle 

 with megasporangia and branch shoot, 5 ( x 40). D, mature mega- 

 sporangia with eight ova ( x 180). (A, after Oltmanns; B-D, after 



Williams.) 



hollow of the vesicle-like internode becomes filled up by new tissue 

 formed as a result of the stimulation, but the parasite is apparentiy 

 unable to attack Hormosira unless the host is growing in areas where 

 it is continuously submerged. 



The fertile conceptacles contain either mega- or microsporangia, 

 the former being much more frequent. Each megasporangium 

 gives rise to eight pyriform zooids (originally beheved to be non- 

 motile ova) that germinate apparently in the conceptacle to a 

 branched filamentous gametophyte with erect colourless hairs. 

 Cells of erect branches can each produce a swarmer which is 

 presumably a female gamete. It seems likely from the construction 

 of the thallus that some of these germinate inside the conceptacle 

 to give a new macroscopic plant. Others must escape and infect 

 Hormosira plants. The microsporangia give rise each to 64 zooids 

 the fate of which is not known. They could presumably either 

 develop to a dwarf male gametophyte or else function as a male 

 gamete. These features are of especial importance in considering 

 the origin of the Fucales (see p. 317). The genus is monotypic and 

 contains the one species, Notheia anomala, 



159 



