XIV.] STONEWORTS. 



trary, undergo division with comparatively little increase in 

 size. And out of them, the nodes, the cortical layer, and 

 all the appendages, are developed. 



In all the young cells of Chara a nucleus of relatively 

 large size is to be seen imbedded in the centre of the pro- 

 toplasm, and the latter is enclosed in a structureless cell-wall, 

 composed of cellulose. As the cell grows larger, the centre 

 of the protoplasm becomes occupied by a watery fluid, and 

 its thick periphery, which remains applied against the cell- 

 wall, constitutes a sac, or primordial utricle, in which the 

 nucleus is imbedded. In the larger cells the primordial 

 utricle is readily detached and made to shrivel up into the 

 middle of the cell by treatment with strong alcohol. In the 

 older cells the nucleus divides up into a number of portions. 



Numerous small green bodies chlorophyll grains are 

 imbedded in the outer, or superficial, part of the primordial 

 utricle, and they increase in number by division, as the cell 

 enlarges. These chlorophyll grains are composed of proto- 

 plasmic matter, which frequently contains starch granules, 

 and is impregnated with the green colouring substance. 



During life, the layer of the primordial utricle which lies 

 next to the watery contents of all the larger cells is in a state 

 of incessant rotatory motion, while the outermost layer 

 which contains the chlorophyll grains is quite still. In the 

 large cells, so long as the nucleus is discernible, it is carried 

 round with the rotating stream. 



The antheridium is a globular spheroidal body with a 

 thick wall, made up of eight pieces, which are united by 

 interlocking edges. The four pieces which make up the 

 hemisphere to which the stalk of the antheridium is at- 

 tached, are foursided, the other four are triangular. From 

 the centre of the inner, concave face of each piece a 

 short process, the handle or manubrium, projects into the 

 cavity of the hollow sphere. At the free end of the manu- 

 M. 28 



