Richards: Ceramothamnion codii 261 



at the base of the tetrasporangium. From this a new tetrasporan- 

 gium starts up, growing into the cavity of the old one and provided 

 with its own thickened wall. This is in turn replaced by another, 

 and yet another, so that one often finds a young tetrasporangium 

 surrounded by the remains of the walls of perhaps four or five 

 earlier ones (Figs. 10, n), something in the manner of the prolif- 

 eration often noticed in the zoosporangia of Saprolegnia. In no 

 instance was more than a single ripe tetrasporangium observed 

 at each node ; in the case shown in Fig. 1 2, the new one has begun 

 its development somewhat earlier than is usual, but no doubt had 

 the older tetraspores been discharged it would have been forced 

 into the empty cavity. This condition of the successive formation 

 of new tetrasporangia within the older ones does not seem to have 



been noted in any other form, a fact which makes the appearance 

 presented by this alga in its tetrasporic stage very characteristic. 



The antheridia, which like the antheridia of the bulk of the 

 Florideae, consist of an aggregation of small cells each containing 

 a single spermatium, originate from the outgrowth of the nodal 

 cells. The latter, dividing into many small cells, spread upwards 

 and downwards from the nodes, usually completely covering 

 the intervening internodal cells (Fig. 22) ; sometimes consider- 

 able portions of a filament are so modified to form one long an- 

 theridium, or, to speak more strictly, a collection of the unicellular 

 antheridia. The spermatium-bearing cells may remain closely ap- 

 pressed to the sides of the internodal cell as is shown in the sec- 

 tion in Fig. 22, or, by reason of a growth more rapid than the 

 lengthening of the internodes, may bulge outwards in more or less 

 rounded masses (Fig. 21). The antheridia were never seen on the 

 same plants as the tetraspores, but usually occur alone, although 

 in a few cases they were observed on the same plant or even the 

 same filament as certain polyspores. 



These polyspores which first attracted attention in their mature 

 condition naturally aroused the suspicion that they might be fav- 

 ellae of the Callithamnion type, especially since the well-defined 

 antheridia described above were also seen. But as the following 

 description shows the most careful search failed to substantiate any 

 such idea, although the development of these spores were worked 

 out in detail. Unfortunately nothing which could be called a 



