76 THE BOTANICAL MAGAZINE. [Voi. xxxiii. >'o. m 



Seki made a seawater of 1.030 in specific weight and saw 

 the spores sink down to the bottom of the beaker. He con- 

 cluded from this experiment that the spores of Porphyra would 

 very likely remain at the bottom of the sea after they were 

 liberated from the jilant in spring until they float on or near 

 the sea-surface and settle on the twigs in autumn, I think 

 the seawater he used is bj' far denser than the water usually 

 met wnth about the culture grounds of Porphyra Hence, his 

 experiment gives a strong evidence for the sinking of the spores 

 soon after their liberation from the mother-frond. 



In the artificial culture tried by Seki, he found the carpo- 

 spores mostly went to -decay before long. Only occasionally he 

 saw some of them protrude a short process as to assume a 

 flask-shape in the • general outline. Further development he 

 could not see. From the result he has obtained from his culture, 

 Seki expressed the view that most of the spores will probably 

 remain ungerminated or in the flask-shaped stage until autumn. 

 This agrees ver\^ well with Berthold's assumption. 



Since my return to Japan, I have been always anxious to 

 try to settle the old question. The coasts of Hokkaido where 

 I live, have no suitable place for the twig-planting for Porphyra 

 culture. I was to carry on m}^ experiments with the " rock- 

 porph^'ra ", i.e., the Porphyra which grows on rocks on the 

 open coasts. For the convenience' sake of observation I chose 

 a flat reef at the entrance of the Oshoro Cove b}' which the 

 Marine Laboratory of the Hokkaido Imperial University stands, 

 and built there a culture ground with a concrete work. 



The result of this exj)criment was quite diflerent from what 

 I had expected, perhaps from what an}' one could imagine. I 

 feel it desirable to give here the account in detail, though in a 

 manner of a preliminarj- note, and not as a concluding one. 



In the vicinit}' of the Oshoro Cove, we find three species of 

 Porphyra occuring almost simultaneoush', viz., P. leucosticta 

 var. suhorhiculatR (Kjellm.), P. linearis Grey, and P. miniata 

 f. amplissima Rosenv. The last-mentioned species is found 

 growing epiphytic on the fronds of Iridaca or on the leaves of 

 Phyllospadix. It never comes out above the water surface and 



