258 Richards: Ceramothamnion codii 



conditions of fruiting. Since this plant lives upon the soft tissues 

 of another alga there are also developed well-marked rhizoids 

 which penetrate between the external cells of the C odium (Fig. i). 

 The prostrate and upright filaments are alike in structure, dif- 

 fering only in the somewhat larger size of the former, which meas- 

 ure from 30-50 /Jt in diameter at the internodes, while the latter 

 vary from about 20-35 I 1 - The structure of the fiiaments is pecu- 

 liar, and at once attracts attention, from its similarity yet unlike- 



ness to that of two other genera of algae. They are monosiphon- 



ous as to the elongated internodal cells (which average 50 [jl long), 

 while at the nodes there are rows of small cells. Such a condi- 

 tion suggests at once Ceramium but the general appearance of 



the cells is far more like those of Callithawnion (Fig. 2). The 

 wall is somewhat thick and the sides parallel, never bulging as in 

 Ceramium, while the chromatophore is very distinct and made 

 up of thickened strands as is usual in Callithamnion. In conse- 

 quence of this the internodes are distinctly red in color, never, as 

 is often the case in Ceramium, quite diaphanous, and it may be 

 added the tips of the young branches are straight, never circinate. 

 The nodal cells, which in the oldest part of the frond are in from 

 three to four rows, lie closely packed between the adjoining 

 internodes. They do not ever, even in the oldest portions of the 

 plant, proliferate downwards and upwards to form a cortication, 

 but only overlap the somewhat tapering ends of the internodal 

 cells, lying in the constrictions formed between the latter, so that 

 they do not produce any marked nodal swellings. Their chroma- 

 tophores are of the same appearance as those of the internodes, 

 but the granulation of the contents is more marked and con- 

 sequently it is of a deeper color. One might describe the gen- 

 eral appearance of the filament as that of Callithamnion and its 

 allies with the addition of nodal cells. 



At the tips of the filaments are found small apical cells, from 

 which the formation of nodes and internodes takes place in an 

 entirely regular manner (Figs. 2, 3). There is first cut off from the 

 apical cell by a transverse basal wall a single indifferent cell. This 

 indifferent cell soon divides from its upper end, by four obliquely 

 anti-clinal walls of small cells which when seen in optical sec- 

 tion are naturally triangular ; the hypothenuse being the newly- 



