FERTILIZATION AND FRUIT-FORMATION IN CRYPTOGAMS. 



63 



concave inner face of each plate a cylindrical or conical cell projects, carrying upon 

 its sunnnit another, capitate, cell. Each of these head-cells is surmounted by long 

 strings of cells, of which the lowest segments are spherical or cylindrical, whilst the 

 rest are short discs (see fig. 206^). The whole structure may be likened to a whip 

 with many thongs, and the stalk-cell projecting from the plate has hence been 

 called the " manubrium " or handle. So long as the eight plates of the sphere are 



Fig. 206,— Fruit-formation in Stoneworts (Characeffi). 



I Cliara /ragilis. ' Piece of tlie same with amplligonia and autlieridia on the branches. 3 A single branch with amphigonia 

 and antheridia. * An antheridium. s a plate of the antlieridium with manubrium and cells grouped in the form of thongs 

 and containing sperraatozuids. •> Several cells from one of the wliip-like lilaments ; the cells in tlie middle contain each a 

 spermatozoid, the spermatozoid is escaping from the uppermost cell, the lowest cell is already vacated. ' A single sperma- 

 tozoid. 8 Amphigonlum inclosing the oogonium, i natural size; 2x10; =X15; <x35; 'xlOO; 6x300; 'x600; 8x60 



closed, these manubria project towards the centre of the hollow sphere, and the 

 rows of cells proceeding from the manubria are conglomerated into a ball. But as 

 soon as the plates separate and the sphere falls to pieces, the ball is untwisted and 

 its parts assume the appearance shown in fig. 206 ^ By this time a spiral sper- 

 matozoid has developed from the protoplasm in each of the discoid segments of the 

 filaments, and may be seen lying within its cell (see fig. 206^). But almost 

 immediately afterwards these cells open, and the spermatozoids, which are provided 

 at one end with a pair of long cilia, escape and whirl about in the surrounding 



