2 M. Tahara. 



naria^ and Sargasstmi^ ^ but only the four with asterisk are found 

 at Misaki. Of these genera only a few species were available for 

 my studies, as the other species did not come to maturity during 

 my stay there. Sargassum énerve, Sargasswn Horneri and Cystophyl- 

 lum sisymhrioides furnished the principal materials of my investi- 

 gation. All these three species are dioeceous. At Misaki Sarga- 

 ssum énerve grows in such profusion as often to present a serious 

 obstacle to the navigation of smaller craft. The liberation of 

 oogonia begins usually at the end of December. 



Sargassum Horneri is also common at Misaki. The receptacle of 

 this species are very large and well-suited for investigation. The 

 liberation of oogonia begins at the end of December. 



Cystophyllvm sisijmhrioides is not so common at Misaki as the 

 former two, but it is by no means rare. The liberation of oogonia 

 begins at about the middle of February. 



First let me give my observations on oogonium liberation. 



I. Oogonium Liberation. 



In the preliminary paper mentioned above, I gave the 

 following acount of my observations on the oogonium liberiation 

 of Sargassum. — At that time I used the term 'Oosphère liberation' 

 intead of ' Oogonium liberation.' But strictly speaking, the 

 products liberated from the female receptacle on the day of the 

 so-called ' Oosphère liberation ' are not oosphères but oogonia 

 containing in their bodies one oosphère initial. 



"On the 24th of December 1908, the next day after the full 

 moon, almost all individuals of Sargassum énerve of the coast dis- 

 charged their oosphères simultaneously. The discharged oosphères 

 stayed on the receptacle for about three days and then dropped 

 off also simultaneously, so that on the 28th there was not a 

 single stock that bore the sporelings on the receptacle. 



'' After a fortnight, i. e. on the day of new moon, the next 

 general liberation of oosphères occurred." 



These facts reminded me of the periodical liberation of sexual 

 products in Dictyota dichotoma and led me to the conclusion that, 

 "The liberation of oosphères in Sargassum takes place simultane- 



