nata (see Fig. 37), or they may, as in Ch. fragilis, closely converge. 

 In the Nitellae the coronula is ten-celled ; the lower five cells are 

 closely adherent, the five upper cells are less adherent, but of larger size. 



In some Nitellae the whole 

 coronula is evanescent and drops 

 off before the maturity of the 

 spore. While the capsule is de- 

 veloping and enclosing the spore, 

 the latter has been growing and 

 developing, in its interior, divis- 

 ions which are not understood 

 (Braun). In the Nitellae the di- 

 vision takes place very early, be- 

 fore the enveloping cells have 

 scarcely attained the length of 

 the terminal cell. At the top a 

 flat disk is set off by a septum 

 extending obliquely backward; 

 then a second, also flat segment, 

 follows, situated beneath the pos- 

 terior wall of the first and reaching 

 down to the base ; lastly, a third 

 resting on the second, is set off 

 from the basal surface. During 

 this process the terminal cell 

 grows on the anterior side so that 

 a distortion of the tip is produced, 



the cell formation progressing Fl^. 41. 



downward and backward, and the anterior wall protruding toward 

 the tip ; on this account the cells just described have been called the 

 "turning cells." In Chara a corresponding division occurs later, 

 when the enveloping cells of the sporostegium have united over the 

 central cell and is confined to a separation of a flat basal cell, like an 

 internal spore pedicle, which is distinctly seen even till the spore be- 

 comes ripe, while the "turning cells'' of the Nitellae, which do not 

 increase in size, become difficult to recognize on account of the pre- 

 mature development of the spore. After the separation of these 

 structures, which seem to be devoid of significance in the farther de- 

 velopment, the remaining part of the terminal cell changes to the 

 ovule, which, when fertilized, ripens into the spore. 



The sporophydium reaches its full size, nearly, before fertilization. 

 The ovule fills completely the cavity of the capsule ; it is at first 



