660 



THE SXZBDIVISIONS OF THE VEGETABLE KINGDOM. 



form a crown surmounting the oogonium (fig. 374^). At fertilization the spermato- 

 zoids penetrate between the cells of the crown, so reaching the egg-cell. The whole 

 oogonium is soon detached and remains dormant through the winter. In the spring 

 it germinates, pushing out a tube which becomes transversely segmented. This is 

 the pro-embryo. From it, as a lateral bud, the adult sexual plant arises. This 

 process resembles that of the Mosses, in which the leafy Moss-plant arises from 



Fig. 374,— Structure and reproduction of Chara/ragilis. 



1 A portion of the plant. 2 A piece of the axis with appendages, upon which are inserted the sexual organs. * A single 

 appendage, showing the flask-shaped archegonia and spherical antheridia. * A single antheridium. 6 a plate of an 

 antheridium with manubrium and whip-like filaments of cells containing spermatozoids. « Several cells from one of the 

 whip-like filaments : the cells in the middle contain each a spermatozoid ; the spermatozoid is escaping from the upper- 

 most cell; the lowest cell is already vacated. ' A single spermatozoid. s Archegonium inclosing the egg-celL 1 nat. size; 

 2x10; 8x16; *xS5; «X100; 6x300; 'x600; 8x60. 



the protonema as a lateral bud. But the comparison with Mosses must not be 

 pushed too far, as in Ghara there is no sporogonium. There are some 67 species of 

 Chara, of which G. fcetida is also very common. Many of them are covered with 

 stiff hairs, and they are for the most part brittle owing to the incrustation of 

 carbonate of lime (c/. vol. i. p. 260). The phenomenon of parthenogenesis in Chara 

 ■crinita has already been described in detail (pp. 463, 464). 



In Ghara stelligera ( — Tolypellopsis ulvoides) the nodes of the stem become 



