CRYPTOGAMS 



181 



plant body is very thin and much expanded, and reaches a 

 length of several feet. In most cases the plants are 

 attached by more or less rootlike holdfasts. The often 

 beautiful color is due to the presence of a red pigment, 

 which more or less completely masks the clilorophyll. 



434. Reijroduction. — A characteristic method of bearing 

 spores is in groups of four (Fig. 299), each group result- 

 ing from the division of the contents of 

 an original mother cell. Such spores are 

 termed tetrasj^ores. They are bright red 

 bodies without cell walls, and being un- 

 provided with cilia, are dependbut upon 

 water currents for dissemination. 



435. Reproduction, with fusion of the 

 reproductive cells, may be illustrated by 

 the case of Nemalion ; this being taken 

 as a simple instance of a process which 



in some members of 

 the group becomes 

 highly complicated. 

 The reproductive cells of Nemalion are 

 poUinoids^ naked spherical cells pro- 

 duced singly in rounded antlieridia 



(Fig. 300, a\ and 

 differing from an- 

 therozoids only in 

 ■^^ being unciliated; 

 and egg cells formed 

 within elongated 

 cells termed carpo- 

 gonia (Fig. 300, c). 



300. Nemalion: ^, showing the carpogonium (c), The Qgg OCCUpiCS 

 trichogyne (0 with pollinoids near, and tlie enlarged basal 

 antheridia (a) ; B, after fertilization, the . ^ -, 

 carpogoninm beginning to branch ; C, the portlOU OI tilC Car- 

 nearly matnre spore-bearing body (cysto- pogonium, the hair- 

 carp, c?/). THURET. -,., , ., r, 



like extremity oi 

 which is known as the trichogyne (t). Several pollinoids, 

 brought by circulation of the water, may adhere to the 



299. Tetraspores (0 

 in a filament 

 of Polysipho- 

 nia. 



