260 Richards: Ceramothamnion codii 



The fact that they must be regarded as merely sterile is of im- 

 portance in another consideration to be taken up later. While the 

 bulk of the material examined was quite destitute of them it is 

 barely possible, although not at all probable, that this condition 

 was brought about by the shedding of the hairs, since indications 

 were seen of their abstriction in certain cases. 



While the structure of the frond of this alga is not without 

 interest the fruit, at least the tetraspore, is more especially note- 

 worthy. Indeed as regards certain features in the growth of the 

 tetraspores the writer has found no mention of a similar condition 

 among other Florideae. As would be supposed the tetraspores 

 are formed at the nodes in the younger portions of the upright 

 branches ; one can easily observe almost all stages on a single fila- 

 ment (Fig. 8). The tetrasporangium itself always arises from a 

 cell in the upper of the two rows of cells at a young node, only a 

 single one developing at one node. After a slight enlargement, 

 chiefly elongation, of this mother cell of the tetraspores the adjoin- 

 ing nodal cells are seen to become actively concerned in the growth 

 (Fig. 8). They begin to grow outwards and around the young 

 tetrasporangium forming bract-like enveloping branches, something 

 like a stichidium with but a single group of tetraspores. The ex- 

 tent to which the enveloping branches develop varies, sometimes 

 only one is produced (Fig. 1 3), representing the prolongation of a 

 single row of nodal cells, sometimes the single row itself branches 

 and forms an almost complete covering to the tetrasporangium, 

 while again several separate rows of nodal cells may develop in 

 this fashion. The tetraspores are not tetrahedral, but are arranged 

 rather in the cruciate fashion, where however the longitudinal di- 

 visions following the first transverse division of the mother cell, are 

 in planes at right angles to each other. When the filaments lie in 

 the position which they naturally assume when attached to the 

 basal prostrate filament, it appears that it is always the distal or 

 upper cell in the young tetrasporangium which has divided in a 

 plane at right angles to the field of vision (Figs. 10, 12, 13). After 

 the spores are ripe the outer wall of the sporangium, which is often 

 considerably thickened, breaks open at the apex and they escape, 

 leaving the empty shell attached to the plant. Then follows a 

 peculiar proliferation, if one may term it so, of the cell which lies 



