REPRODUCTION OF ULOTHRIX 



213 



The products of division (sp.), each of which has a chloroplast 

 and pyrenoid of its own, are liberated through a small round 

 hole formed in the side-wall, but remain enveloped for a few 

 seconds in a thin bladder of mucilage (Fig. 115, b). Meanwhile 



FIG. 115. Ulothrix zonata. a, two young plants recently developed 

 from zoospores ; b, thread showing stages in the development of 

 zoospores (sp.) ; c, short length of vegetative filament showing 

 chloroplasts (c) with pyrenoids (p.) ; d, zoospore ; e and /, young 

 plants developed from zoospores ; g and h, two forms of zygospores ; 

 i, germination of same ; j, gamete ; k and /, stages in fusion of 

 gametes ; m, the resulting zygote ; n and o, stages in development 

 and liberation of gametes (g.). ax., attaching cell, (b and c, j-m f 

 after Klebs, all the rest after Dodel-Port.) 



each portion has developed four cilia, two contractile vacuoles, 

 and an eye-spot, so that in all essential respects it resembles a 

 naked Chlamydomonas. 



The pear-shaped motile elements thus formed are the 



