CARPOSPORE^. 



295 



node, the ascending and descending lobes dove-tailing in a prosenchymatous manner. 



The formation of the cortex takes place so early that the elongating internode is 



;overed by it from the first, the lobes keeping pace with its extension in length and 



lickness. Each lobe continues to grow, like the stem, by means of an apical cell, which 



)ecomes segmented by transverse septa ; out of each of the segments cortical internodal 



md nodal cells are formed by repeated divisions. The latter divide, by successive septa, 



[into an inner cell (Fig. 194, Z), c), in contact with the internode of the stem, and three 



)uter cells, the middle one (/) of which commonly grows into the form of a spine or 



:nob, resembling a leaf. The outer lateral cells {n n) of the cortical node, on the other 



land, following the elongation of the internode itself, grow into longer tubes, so that 



;ach cortical lobe consists of three parallel rows of cells, the middle row however 



:ontaining alternately short and long (internodal and nodal) cells. The cortex of the 



leaves is derived from the leaflets, and its formation is much simpler (Fig. 193, C-E, br). 



'rom the basal nodes of Chara other foliar structures also arise, both on the inner and 



)uter side of the base of the leaf (Fig. 192, 6), which Braun calls Stipules; they are 



ilways unicellular, and are sometimes very short, sometimes elongated. 



The nodes are the parts from which all the lateral members of the Characeae 

 )riginate. The root-like structures or Rhi%oids spring from the outer cells of the 



Fig. 194. — Development of the cortex of the stem of Chara fragilis ; A a very young internode of the stem with the 

 cortical lobes r still consisting of one cell ; R—D its further development ; r r signifies in all the figures the cortical lobes 

 that ascend from the lower, r' r' those that descend from the upper leaves ; v v the apical cell of each cortical lobe ; ^^ its 

 internodal cells ; n nt n the commencement of the formation of the node ; D c the central cell of a cortical node ; .S" signifies 

 in all the figures the unicellular ' stipules' which spring in pairs from the base of the leaves. 



)wer nodes of the primary shoot, and consist of long hyaline tubes growing obliquely 



lownwards, and elongating only at their apex. They are formed by the outgrowth 



)f flat cells at the circumference of the node, and are therefore attached to it by 



broad base; but the bases of the stouter rhizoids themselves divide still further, 



[giving rise, especially at the upper margin, to small flat cells from which slender 



jrhizoids are developed. The rhizoids are segmented by only a few septa which lie 



[far behind the growing apex, and have at first an oblique position. The two ad- 



f joining cells abut upon one another like two human feet placed sole to sole. The 



(branching always proceeds only from the lower end of the upper cell (Fig. 195, B)\ 



|a swelling is here formed which becomes cut off by a wall, and by further division 



)roduces several cells which grow into branches; these therefore stand on one side 



[like a tuft. The tubular cells composing the rhizoids attain a length of from several 



lillimetres to more than two centimetres, with a thickness of from tV to tV mm. 



The Vegeiati've Reproduction of Characeae always proceeds at the nodes, and has 

 three modifications: — (i) Tuberous formations called Bulbils (starch-stars) which occur 

 in Chara stelligera. They are isolated underground nodes with greatly abbreviated 



