ALGAE. CHARACEAE. 63 



basal node of the leaf. The leaf shows three lower internodes s, s, s, which are at present 

 short ; they may become six to eight times longer ; between them are the leaf-nodes 

 w, w ; v, v are the cells which connect the' leaf-node with the basal node of the leaflet 

 /3 on the outer side of the leaf, a the corresponding cells on the inner side ; rthe cortical 

 lobes of the leaf, two of which ascend and two descend from each leaflet ; the lowest 

 internode of the leaf is however covered only by descending lobes ; by the side of one 

 of them is the stipule j ; .r, x are the descending cortical lobes of the internodes of the 

 leaf on their inner side, where the leaflets are transformed into antheridia a, a ; the 

 ascending cortical lobes are wanting here, because one oogonium alway arises from 

 the basal node of each leaflet (cp. Fig. 35, A and B). With respect to the origin of the 

 oogonium, Braun says at p. 69 of the work cited above, that just as a twig springs from 



FIG. 41. C hara fragil 



A lower part of a fertile leaf, from the axil of which a lateral shoot is springing (see the text). 

 >wer part of a sterile leaf without an axillary shoot (in longitudinal section). 



B lower \ 



the basal node of the leaf, so the oogonium springs from the basal node of a leaflet (in 

 Chara fragilis of an antheridial twig, which there takes the place of a leaflet) ; as the 

 branch-bearing leaf has no ascending cortical lobes, so the leaflet, which bears the 

 oogonium, has none ; as it is the first leaf of the whorl on the stem which produces a 

 branch in its axil, so it is the first (inner) leaflet of the whorl on the leaf with which the 

 formation of the oogonium is connected. The basal node of the antheridial twig in 

 Chara fragilis has, according to Braun, not four peripheral cells, as in sterile leaflets, 

 but five ; one odd one above, the first formed, two lateral ones formed next, and two 

 lower ones, the last formed. Of these five cells only the two lower become cortical cells 

 (of the leaves) ; the upper, which is wanting in the sterile basal nodes, is the mother-cell of 

 the oogonium ; the two lateral cells develope into leaflets, which are placed at the side 



