12 



ZYGNEMATACEAE 



TABLE I 



Summary of the OBstRvto 



Usual Methods of Reproduction among the Zygnemataceae 



Of the 494 species that usually reproduce by zygospores, 77 some- 

 times also reproduce by aplanospores. These species are distributed as 

 follows: Spirogyra, 25; Mougeotia, 25; Zygnema, 16; Zygnetnopsis, 5; 

 Zygogonium, 2; Debarya, i; Temnogametum, 2; and Sirocladium, i. 



