SIPHON GREEN ALG& 



227 



ponds, lakes, streams, or on damp soil. The threads are long, 

 branched, and continuous, that is without cross walls except where 

 reproductive organs or cells " i \ 



are formed. The plants / ' 



usually form dense mats of 

 a coarse consistency and are 

 known as "green felts," be- 

 cause of the felted consist- 

 ency of the mats. Asexual F >g- l8 ?- 



, v , Vaucheria sessilis; oogonium opening and 



reproduction IS Dy large emitting a bit of protoplasm; sperms; sperms 



e , e .1 entering oogonium. (After Pringsheim and 



spores formed from the pro- Goebei.) 



toplasm in the ends of the threads separated by a cross wall. 



Fig. 188. 



Fertilization in Vaucheria. mn, male nucleus; fn, female nucleus. Male nucleus entering 

 the egg and approaching the female nucleus. (After Oltmanns.) 



Some of these spores are motile, \vith numerous pairs of cilia over 

 the surface, while others are non-motile. These spores escape from 



In 



, 



I^B>1 



Fig. 189. 



Fertilization of Vaucheria. fn, female nucleus; mn, male nucleus. The different figures 

 show various stages in the fusion of the nuclei. 



the enclosing cell wall. In sexual reproduction specialized short 

 branches are formed, which are separated from the parent wall 



