SOME NEW ALGÆ FROM JAPAN. 285 



The antheridia are also fusiform with broad bases, and measure 

 half the diameter of the stichidia. The colourlessness of the 

 tetrasporangia makes it difficult to distinguish the antheridia 

 from the stichidia with the naked eye. Under the microscope, 

 however, the characteristic antheridial form of the Rhodomelaceœ 

 is immediately recognized. 



While yet very young, each antheridium has an axial row 

 of cells, each, except the terminal one or two, surrounded by 

 four pericentral cells (Fig. 5). The further divisions of the peri- 

 central cells are three cells from each, answering to the two 

 guard and one basal cell of the stichidia. Both of the former 

 two again divide to generate two pollinoids, and the latter, four. 

 Thus each pericentral cell gives rise to eight pollinoids arranged 

 in two transverse layers. The co-genetic pairs of pollinoids stand 

 close together. This arrangement may become quite obscure as 

 the antheridia attain to maturity. 



The cystocarps are globular and sessile, and are attached to 

 the wart-like protuberance with a comparatively narrow base. The 

 mature cystocarps measure 0.43—0.52 mm. in diameter, and may be 

 readily distinguished from the two other reproductive organs with 

 the naked eye. They are also colourless. The number of cysto- 

 carps in one aggregation amounts to 40 — 70. Unlike the ordi- 

 nary forms of cystocarps of the Rhodomelaceœ, they are quite 

 globular and have no definite carpostome. The pericarp is 

 constructed with several layers of angulate cells disposed rather 

 irregularly. The cells lining the inner wall are somewhat flat- 

 tened and broad, and those on the external surface, more or 

 less isodiametrical. The cells in the placental region, however, 

 are much larger and polygonal, resembling those which build up 

 the protuberance. 



The behaviour of the carpogonal cells during fertilization 

 has not been observed, as almost all the cystocarps found in 

 the material have nearly attained maturity. The result of the 

 cell-fusion after fertilization is the formation of four or five 



