Fig. 113 Fucus. Aj transverse section 'female' conceptacle of F. 

 spiralis var. platycarpus. B, transverse section 'male' conceptacle of 

 F. vesiculosus. C, portion of thallus of F. spiralis to show structure 

 ( X 125). D, origin of hyphae i cm. below apex, F. spiralis ( x 235). 

 E, antheridia (microsporangia). F, young, and G, old oogonium 

 (megasporangium).H, liberated ova. e =endochiton,m =mesochiton. 

 I, ova being liberated, e =^ endochiton, w =mesochiton. J, empty 

 sporangium showing torn exochiton. K, ovum being fertilized. L, 

 antherozoid. (C, D, after Pennington; rest after Oltmanns.) 



where they come from adjacent tissue. This method of for- 

 mation occurs in Sargassum, Bifurcaria, etc. The tongue cell 

 and apical cell of the Hnear series are regarded as vestigial 

 hairs so that the conceptacles really originate from the basal 

 cell of a hair. 

 The cryptostomata or hair pits are regarded as a juvenile stage of 

 the fertile conceptacle, because sporangia are frequently associated 

 with the hairs, or else hairs occur in the same cavity after the 

 sporangia have been lost. It has also been suggested in the past that 

 the cryptostomata may represent abortive sexual conceptacles which 

 fail to develop, or alternatively that they are structures which have 



201 



