414 AQUATIC PHYCOMYCETES 



Strasburger noted that the colorless zoospores were phototactic, a 

 curious physiological adaptation to their mode of life, that is, preying 

 on motile algae. 



Though the fungus was placed by Minden (following Fischer) in 

 Rhizophlyctis, Strasburger clearly states that the zoospore upon coming 

 to rest rounds off and ". . .entsendet nun von einer Stelle aus, der 

 Cilieninsertionsstelle so schien es mir, die sich baumartig verzweigenden 

 Keimfaden aus." 



Rhizidium windermerense Canter 



Ann. Bot. London (N.S.), 14:268, figs. 1-4, pi. 8, A and B. 1950 



(Fig. 11 J, p. 110) 



"Thallus monocentric, eucarpic, polyphagous, consisting of a sporan- 

 gium (the body of the encysted zoospore) and a single main rhizoidal 

 axis which by the development of secondary branches loses its original 

 taproot-like appearance. Sporangium inoperculate, pear-shaped, 8 \l 

 high by 6 [jl broad to 26 \i high by 23 \x broad, containing from 5 to over 

 60 zoospores. Zoospores spherical, uniguttulate and uniflagellate, 

 emerging in an undifferentiated mass. Zygospore spherical to sub- 

 spherical, 14-17 jjl in diameter, wall thick, smooth, sometimes yellowish, 

 content consisting of numerous small globules; formed after conjugation 

 of the tips of the rhizoids from two thalli, the contents of both passing 

 out to form a swelling, the incipient resting spore at their point of fusion. 

 Rhizoidal system as in the sporangium developing after fusion of the 

 sexual thalli. The latter remain as empty appendages (2.6-5.9 \i diam.) 

 on the rhizoidal system of the mature spore" (Canter, loc. cit.). 



Parasitic on the planktonic alga Gemellicystis neglecta (Teiling) 

 Skuja, Canter {be. cit.), Great Britain; host?, Canter (1951: 153), 

 Italy. 



The sexual formation of the "zygospores" (resting spores) is discussed 

 under the genus (p. 408). 



Rhizidium braunii Zopf 



Nova Acta Acad. Leop.-Carol., 52 (7): 349, pi. 23, figs. 1-7. 1888 



Rhizophlyctis braunii (Zopf) Fischer, Rabenhorst. Kryptogamen-Fl., 1 (4): 

 120. 1892. 



