STRUCTURE AND DEVELOPMENT. 



27 



normal branchlet has three or more nodes, and is 

 terminated by a more or less conical or acuminate 

 apical cell either immediately above the highest node, 

 or with one or more elongated cells intervening. Each 

 node gives rise to a whorl of small 1 -celled lateral 

 members, termed bract-cells arising from the periphery 

 of the node (Fig. 6/0, normally elongated, growing 

 outward and taking an upward direction. On the 

 outer side of the branchlet the bract -cells are usually 



C /OQD 



II 



FIG. 6. Portions of young' branchlets. i-i v. Cha rafragilis (after Sachs 

 and Prosper), v. Chara delicatula (after Kuczewski) ( x c. 150). 

 i. Axial section of very young branchlet, before peripheral cells of 

 node have become subdivided, ii. Transverse section of node of 

 rather older example, iii and iv. Exterior view and axial section 

 of two nodes of the same. v. Exterior view of two secondary (peri- 

 pheral) nodes, a, terminal cell; b, penultimate cell; c, nodes, early 

 stage ; d, interned al cells ; e, central cell of nodes ; /, intermediate 

 cell of ditto ; g, cortical cells ; h, bract-cells ; i, rest-cells. 



shorter than on the inner, and are often rudimentary. 

 The bract-cells vary considerably in different species 

 in regard to shape, length and thickness. They are 

 usually cylindrical, and more or less acute, but some- 

 times blunt, at the apex. In a few species they are 

 almost as broad as lono* and subglobular. In addition 



o o 



