86 'J^HE BOTANICAL MAGAZINE. ^voi. xxxni. No. m 



in the similar way as the asexual spores. But he appears to 

 have believed it to be so, only the carpospores germinating 

 very slowly after a long resting periocV\ 



I have not studied the behaviour of the asexual spores of 

 our Porphyra. If Berthold's statement about the asexual 

 spore be true for all Porphyra, there must be a continuous 

 grow of the plant whole the year round. Generally, however, 

 in warm countries, the Porphyras entirely or almost disappear 

 during summer months. 



Cotten'^^ states about the marine vegetation of the Clare 

 Island that the growth of Porphyra " occurs more or less 

 throughout the year, though it appears to be more abundant 

 in spring and autumn than in summer." He reports 3 species 

 and 2 varieties of Porphyra to occur on the Island. But he 

 does not touch the point whether the continuous vegetation 

 is of the same species or by alternation of different species. 

 Still, from his statement above cited and from detailed descrip- 

 tion of various localities of the Island, we can understand that 

 Porphyra-vegetation thereabout is not uniformly continuous 

 all the year round. 



RosENYENGE^^ remarks that P. leucosticta seems to dis- 

 appear and P. uwbilicalis disappears entii-ely or almost entirely, 

 during summer on the Danish coasts. Kjellman observes 

 similar thing on the Swedish coast of the Skagerrack. (Cfr. 

 BoKGESEN : The Algae vegetation of the Faeroese Coasts, 

 p. 717). 



In his excellent work on the marine vegetation of the 

 Faeroese Islands, Borgesen describes the Porphyra and says 

 that " it seems to be well developed all the year round, and is 

 not, as Simmons says, mostly a " winterformation " on the 

 exposed coasts, even if it may be supposed to be still more 

 vigorously developed in winter, judging b}' its growth in other 

 places " (p. 717). He attributes this continuous vegetation of 

 Porphyra on the Islands to the roughness of the sea and con- 



1) Bbbtjiold: Bangiaceen. p. 29. 



2) Coiton: Clare Island Survey, Marine Algae, p. 57. 1012. 



3) Rosknvenge: The Marine Algae of Denmark, I'art 1, p. 6fi. 



