21 



In Chara evoluta, Allen, a little higher development is attained. 

 The cortex node bears two spines, while one of the lateral cells makes 

 a feeble attempt at developing lateral cortex tubes. 



Fig. 26, a portion of the cortex of Ch. evoluta, Allen, showing 

 two nodes ; on one side of each node a small lateral cortex cell 

 has formed, \vhile the node bears two spines, instead of three, as in 

 Ch. crinita. 



In case one lateral cell develops fully and extends up and down 

 to meet the other lateral cell, then a double cortication results. This 

 is well seen in Ch. excelsa, Allen, which, in size and general aspect, 

 closely resembles Ch. crinita and Ch. evoluta. It is also found in our 

 very common Ch. fcetida, and Ch. contraria, species which represent 

 two clearly defined sub-divisions of the diplosticlie series. 



In Ch. contraria (also in Ch. intermedia, Ch. excelsa, et cetera), the 

 primary cells of the cortex system (the cells which carry the nodes), 

 attain a larger development, while the secondary, lateral cells, re- 

 main smaller, so that in a cross section there appears an alterna- 

 tion of larger and smaller cells, the larger belonging to the primary 

 (median) row of cortex tubes. On the surface we see an uneven- 

 ness, the papillae or spines are borne on the larger cells and seem 

 to be on the top of a ridge, while the smaller lateral cells are 

 partly hidden between these median cells. This series of Charae 

 is called ' ' tylacanthce. " 



Should, however, the lateral cells grow to a larger size than the 

 median, then the nodes, with their papillae or spines, seem to lie 

 in a valley between the higher lateral cells ; this series is termed 

 " aulacanthce, " and is typified by our very common Ch. fcetida, 

 A. Br. 



STIPULES. In the development of cells in the basilar node of 

 the leaf, two or three cells at the base of each leaf arise, superficial 

 to the parent cortex cells, and protrude as papillae, or develop into 

 more or less extended appendages called, by Braun, Stipules. These 

 stipular cells remain as simple, undivided cells, though they may 

 attain a considerable length. 



In Ch. stelligera, whose stem has no cortex, there are three small 

 stipular cells at the base of each leaf, but they do not develop farther 

 than minute papillae. In Ch. corona/a a single stipule develops on one 

 side of each leaf, so that the stipules equal the number of the leaves 

 and seem to alternate with them (see Fig. 27). 



