Sept., i92o.] OKAKUEA, ONDA & HIGASBI.—PORPHYRA 133 



we began to suspect that they were rhizoidal filaments. Starting 

 from this idea we conceived that immature carpospores may emit 

 rhizoids to absorb nutritive material; because they will not have at this 

 time accumulate sufficient reserve materials so as to divide in a row 

 resembling the young fronds, which we met with in sporelings normally 

 germinated in autumn. Based on this idea we prepared several 

 samples of culture medium containing different quantities of nutrients 

 in the sea water of the same specific gravity as the others. In a 

 culture containing 0A% of Sodium Nitrate, 0.2% Calcium Nitrate and 

 0.4^ Potassium Nitrate, the majority of the spores did not emit 

 rhizoidal filaments, while others did, but they were much shorter 

 than those in dilute culture mediums and they took much longer time 

 to send out roots. 



In a dense fluid spores divided into three or even more, while 

 those in dilute medium, Sodium Nitrate 0.2^ and a trace of Calcium 

 Phosphate, developed much longer filaments in a shorter time. 



In a culture containing a sample which was collected at Kisaradu 

 on Jan. 19th, we observed 19 days later, i.e. Feb. 6th, several spores 

 divided into two (Fig. 6J. Later in a hunger culture collected at 

 Honmoku near Yokohama on Feb. 8th, we found on March 23th. not 

 a few sporelings which had divided into 7-10 cells in a row from a carpo- 

 spore (Fig. 9), while many spores remained in an undivided stage. In 

 the same culture there were some forms which had developed a spore- 

 ling as a branch of the rhizoidal filament (Fig. 9c), so the filaments may 

 not be considered only as true rhizoids, but they have or may have the 

 character of protonema, though their chief function seems to absorb 

 nutrition. That the forms which we just mentioned above as spore- 

 lings are really young fronds which developed from a carpospore 

 might not be said to be established unless we could culture it. up into 

 fully grown fronds, yet there is another evidence to substantiate the 

 claim of its being sporelings. At Tateyama on March 7th, one of the 

 colloborators collected Porphyra suborbiculata Kjellm., which bare 

 fully ripened carpospores. The fronds were put in a beaker and the 

 liberated carpospores dropped to the bottom. After 10 days the spores 

 were taken out on a glass slide, the water being carefully decanted 

 off, and placed in a culture of sea water containing a trace of Calcium 

 Phosphate and 0.2^" of Sodium Nitrate. On April 1st, almost all of 

 the spores thus treated were seen to have developed into young fronds 

 of different stages, producing rather long and colorless root fibres, 

 which we can take for nothing but young fronds as are generally seen 



