THAU A. 



205 



.^isnt cells, each of which then liberates an anthero- 

 zoid. The antherozoids make their way down the necks 

 of the earpogonia and fertilize the germ-cells. The spiral" 

 cells then harden, and form a firm coat for the spore 

 within. As .the plant decays in the autumn, these seed- 

 like sporocarps, as they are now called, drop off and fall 

 to the bottom of the water, where they eventually ger- 

 minate. On germination, they first 

 produce a simple form to which the 

 name pro-embryo has been given, 

 and from which arises the plant- 

 body which bears the antheridia 

 and earpogonia. 



There is, therefore, displayed in 

 this case an alternation of genera- 

 tions. 



355. Chara belongs to a group of 

 Fig. 255. plants known as Algge. They 



grow either in the water or upon damp surfaces. They 

 differ from the Fungi principally in developing chlorophyll, 

 so that they are able to assimilate. In colour, the Algae 

 are often green, but in other cases the chlorophyll is 

 obscured by the presence of other colours, such as brown 

 and red. In the lowest forms of both Algae and Fungi 

 reproduction takes place by simple division of the cells. 

 In higher forms the entire contents of two similar adjacent 

 cells coalesce to form a new one, from which the new 

 plant springs. This is the process of conjugation (284). 

 In still higher forms, as in Chara, reproduction takes place 

 by fertilization. 



Fig. 255. Highly magnified view of part of the fertile thallus of Chara. 

 (Thom<.) 



