39 



3 ~^ome cortex-nodes develop spines but no secondary tubes; 



the primary tubes join and completely encircle the stem : e. ^,, Ch 

 crinita. 



4.— Some cortex-tubes show a partial development of secondary 

 tubes, as in Chara evoluta, Allen. 



5.— Some cortex-tubes develop one secondary cell only, which 

 becomes as long as the primary cell, but smaller in size, as in Chara 

 excelsa, Allen (also Chara intermedia^ A. Br., Ch, coniraria, A. Br.). 

 (Section Tylacanthae.) 



6.— Some develop only one lateral cortex-cell, which becomes 

 larger than the primary cell and partially covers it, so that the pri- 

 mary cell seems to lie in a valley (Section Aulacanthae); for example, 

 Ch. foetida^ A. Br. 



7.— Some cortex-cells develop perfectly one lateral cell and im- 

 perfectly another, as, for example, Ch. aspera, 



8.— Some cortex-cells develop perfectly both lateral cells, so that 

 three complete series of cells arise from each leaf, as in Ch. fragilis 

 (also in Ch. gynmopiis, A. Br.). 



In Plate xv the figures correspond to the divisions given above. 

 In Chara aspera the greatest variability may be observed (Fig. 7 from 

 true aspera, Canada, and 7^ from var, Macounii). In Fig. 7 the sec- 

 ondary cells meet obliquely, while in 7^ one of the secondary cells 

 extends past the other, so that a section of the stem at this points 

 would show more than double the number of cortical tubes as compared 

 with the leaves of the verticil. Fig. 7^ was taken from a form of Ch. 

 asperaQ) from Fort Pond, Long Island; unlike those of the typical Ch. 

 aspera, the secondary cells join with square and not obliqe ends, and 

 these cells never or rarely overlap, as in true aspera\ but the irregu- 

 larity of the cortex is produced by the partial and irregular develop- 

 ment of secondary cells from the ^opposite side of the node of the 

 primary cell. 



I have been unable to find subterranean bulblets on this plant, 

 and a thorough examination may show affinities rather with Ch. 

 Krausii (whose secondary cortex-cells join rectangularly) than with 

 Ch. aspera. In Fig. 8 is represented a typical triplostichous cortex in 

 which cells develop from both sides of the node to the primary cell and 

 extend upward and downward to join cells from neighboring nodes. 

 In Fig. 8a is represented an anomaly, sometimes noticed, in which, 

 by reason of an unusual extension of some cells, the cortex becomes 

 hyper-triplostichous. In Fig. 8^, x, x represent the primary tubes; 

 d^ a normal secondary tube which meets / below and extends above 

 tor, the latter overlapping and extending down to meet a, which in turn 

 has overlapped b and extended up to meetr. At b — //there are three 

 series of tubes between the primary series. Both Chara fragilis and 

 Ch. gymnoptis are, as a rule, regularly triplostichous ; the former as 

 regards the stem only, the latter both in stem and leaf. 



Chara coronafa^ 7az. — A description of the various forms of this 

 species has been given recently in the American Naturalist^ and it is 

 unnecessary to reproduce it here. The cortex-cells of the basilar 

 node of the leaf are rudimentary and the stems are entirely devoid of 

 any cortex development. Plate xvi, illustrating one of the American 

 varieties of this species, has been used in the American Naturalist. 



