STRUCTURE AND DEVELOPMENT. 



35 



growing cells, styled spine-cells (Fig. 10 c). Each node- 

 cell may produce one, two, or a cluster of these. In 

 some species subglobular intermediate cells, whicli 

 Mr. A. W. Hill has styled head-cells, are produced 

 between the node-cell and the spine-cells (Fig. 10 d). 

 The spine-cells are extremely diverse in size and 



FIG. 10. Cortex of Chara aculeolata (after Hill), i. Longitudinal 

 section of an upper and a lower cortical series at an early stage, 

 showing development of spine-cells, ii. Longitudinal section of 

 mature cortex-node, iii. Transverse section of the same, a, nodal- 

 cells ; I, internodal-cells ; c, spine-cells ; d, head-cells ; e, lower 

 stipulode. The shading in ii and iii indicates the presence of starch. 



shape, ranging from minute almost spherical or very 

 shortly-conical processes to thin sharp spines several 

 times as long as the diameter of the stem. They are 

 usually deciduous and therefore absent on the older 

 parts of the stem. 



The spine-cells nearer the stem-nodes are often 

 more developed than those towards the middle of the 



