86 



Chlorophycece 



ponds and ditches. The macrozoogonidia and microzoogonidia 

 possess two cilia in some species, but four in others 1 , and they are 



produced singly or in num- 

 bers from almost all the cells 

 of the thallus (fig. 28 B). 

 The gametes are biciliated 

 (fig. 280 and F) and the 

 zygospores are either smooth 

 or stellate. Iwanoff states 

 that the macrozoogonidia 

 germinate directly, but that 

 the microzoogonidia pass 

 into a resting stage. 



Fritsch 2 has recently 

 published some interesting 

 observations on early stages 

 of development of this genus. 

 He finds the development of 

 the basal portion to vary very 

 much in different species and 

 also to some extent within 

 the limits of each species. 

 He also concludes that cer- 

 tain plants described under 

 the generic name Herpo- 

 steiron are merely stages in 

 the life-history of epiphytic 

 " Stigeoclonia." 



Hazen 3 has given full 

 and conclusive evidence that 

 Myxonema was well estab- 

 lished before the .publication 



of Kiitzing's genus Stigeoclonium, and sentimental reasons cannot 

 therefore stand in the way of the abandonment of the generic 

 name " Stigeoclonium." 



There are several British species of this genus, of which the most frequent 

 is M, tenue (Ag.) Rabenh. (tig. 28). M. amcenum (Kiitz.) Ha/en is also 

 another widely distributed species. 



1 Iwanoff in Bull. Soc. Imp. Nat. Moscou, 1899. 



2 Fritsch in Beihefte zum Botanischen Centralblatt, 1903, Bd xiii, Heft 4. 



3 Hazen in Memoirs Torr. Bot. Club, 1902, xi, no. 2, pp. 1934. 



Fig. 28. Myxonema tenue (Ag.) Eabenh., 

 from near the Lizard, Cornwall. A, part of 

 thallus (xlOO); B, escape of zoogonidia; C, 

 escape of gametes; D and E, zoogonidia; F, 

 conjugation of gametes; G, development of a 

 cluster of zoogonidia ( x 500). 



