196 



PHAEOPHYCEAE 



one gives rise to the walls of the conceptacle. This method of forma- 

 tion has been successfully demonstrated for Sargassum, Pycno- 

 phycus and other Fucaceae. It is clear from the investigations that 

 have been made that both methods (2) and (3) are to be found in the 

 different species. 



Fig. 131. Fucus. A, transverse section "female" conceptacle oi F. platy car pus. 

 B, transverse section " male " conceptacle of F. vesiculosm. C, portion of thallus of 

 F. spiralis to show structure ( x 125), D, origin of hyphae at i cm. below apex in 

 F. spiralis ( x 235). E, microsporangia. F, young, and G, old megasporangium. 

 H, liberated ova in inner vesicle, e = endochiton, m = mesochiton. I, ova being 

 liberated, e = endochiton, 7M = mesochiton. J, empty sporangium showing torn 

 exochiton. K, ovum being fertilized. L, antherozoid. (C, D, after Pennington; 

 rest after Oltmanns.) 



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

 the fertile conceptacle (cf. also p. 178) because sporangia are 

 frequently associated with the hairs or else they occur in the same 

 cavity after the hairs have been lost. With this interpretation in 

 view the following morphological series can be arranged : 



