] M. Tahara. 



sporeliiîgs become fastened to the bottom of glass basin and may 

 also be used for investigation. 



Generally speaking, the oosphères of S. Honieri, S. énerve and 

 Cyst, sisymhrioides are equally oval or elliptical and common to all 

 of them the first segmentation wall runs perpendicular and about 

 midway to the long axis of the oosphère (Fig. 2, PL. Ill; Fig. 5, 

 PL. Ill): the second wall runs parallel to the first, cutting ofï a 

 small lens-shaped cell at one end of the sporeling. Nienburg 

 states in his paper, " Die erste Wand steht senkrecht zur Läng- 

 sachse. Die zweite steht senkrecht auf der ersten und teilt das 

 Vorderende in zwei gleiche Hälften. Darauf wird von der unteren 

 Spitze durch eine Wand, die der ersten parallel ist, eine schmale 

 Rhizoidzelle abgeschnitten." Thus his observations do not agree 

 with mine. 



Further development differs in Sargasswn and Cystophyllum, 

 and would better be described separately. 



Sargassum. 



The lens-shaped cell, cut off by the cecond segmentation wall 

 will hereafter be called for the sake of convenience the ' Rhizoid 

 cell.' This cell divides simultaneously with the segmentations of 

 the other cells, until the eight-celled stage is reached. The segmen- 

 tations of the rhizoid cell are quite regular and the segmentation 

 wall are all perpendicular to the outer surface of the sporelings. 

 (Figs. 5, 8, 9, PL. II) clearly show this regularity. While the 

 segmentation of the other cells proceeds further, the rhizoidal 

 portion remains in the eight-celled stage, and in the mean time 

 the rhizoid formation begins. At the outset, we see the papilla- 

 like protuberances, eight in number (Fig. 11, PL. II). These 

 protuberances grow gradually and become a group of rhizoids 

 arranged in a circle. But later there arises in the central region 

 another group of rhizoids which elongate with greater rapidity so 

 that they become longer than those of the first and outer group 

 (Figs. 13 and 14, PL. II). This difference in length becomes, 

 however, obscure in the further development of the rhizoids, the 

 outer group of rhizoids also growing rapidly (Fig. 15, PL. II). 



