176 CHARACE^ 



usually broken up into a number of fragments. The current is most 

 rapid next to the stationary parietal layer, and becomes gradually slower 

 towards the interior. As the cell grows the rotating protoplasm becomes 

 differentiated into a watery and a less watery denser portion, the former 

 having the appearance of a hyaline cell-sap, in which the latter floats in 

 the form of larger or smaller roundish lumps. Since these denser bodies 

 are passively swept along by the clear rotating protoplasm, the appear- 

 ance is presented as if the cell-sap caused the rotation. Together with 

 the denser lumps of protoplasm of less regular form, there are also a 

 number of globular masses carried along in the current, which are 

 covered with delicate protoplasmic spines or cilia ; their nature and 

 function are involved in obscurity. 



Owing to the large size of the cells and the distinct differentiation of 

 the nucleus, the internodal cells of the main axis of Chara and Nitella, 

 as well as the apical cells of the leaves, have been largely used for fol- 

 lowing the complicated processes connected with cell-division and the 

 division of the nucleus. Schmitz describes the process as one of 'direct 

 division of the nucleus,' Treub and Strasburger as one of 'fragmenta- 

 tion ; ' Johow differs in some respects from all previous observers ; 

 Cagnieul (Bull. Soc. Bot. France, 1884, p. 211) finds the process espe- 

 cially easy to follow in the mother-cells of the antherozoids. Schaar- 

 schmidt (Bot. Centralblatt, vol. xxii., 1885, p. i) describes peculiar cell- 

 wall thickenings and grains of 'cellulin' in Chara hispida (L.). 



The Characeae do not produce spores, i.e. single non-sexual pro- 

 pagative cells ; but are multiplied non-sexually in three different ways, 

 the nodes being always the place of origin of the propagative cells, 

 (i) Chiefly in Lychnothamnus stelliger (A.Br.), but also in C. hispida, 

 C. aspera (^^"illd.), and Lamprothamnus alopecuroides (A.Br.), structures 

 called ^z^/i5//r or 'amylum-stars' are formed, agglomerations of cells deve- 

 loped round the larger internodal cells at the level of the nodes ; they are 

 of beautiful regularity, and are densely filled with starch and other food- 

 materials. On_ germinating they appear to produce at first other bulbils, 

 and from these a new plant. (2) Chara fragilis and other species produce, 

 on old hibernating or on cut nodes, in the axils of the leaves, peculiar 

 branches known as gymnopodal shoots, which differ from the ordinary 

 branches in the partial or entire absence of the cortex in the lowest 

 internode and in the first whorl of leaves. The cortical branches which 

 descend from the first node become detached, bend upwards, and pro- 

 pagate themselves. (3) Also on C. fragilis, Pringsheim describes the 

 occurrence of 'pro-embryonic,' or more properly oi prothalloid branches. 

 These also spring from the nodes of the main axis, but differ essentially 

 from the ordinary branches, presenting a similar structure to the pro- 



