782 AQUATIC PHYCOMYCETES 



From the color of the zoospores it appears possible that here, as in 

 Woronina glomerata, solid particles are ingested. 



OCTOMYXA Couch, Leitner, and Whiffen 

 J. Elisha Mitchell Sci. Soc, 55: 400. 1939 

 (Fig. 58 F-J, p. 778) 

 "Parasitic on Achlya causing hypertrophy of host. The infecting zoo- 

 spore giving rise to a naked protoplast, which at maturity forms a large 

 spherical sorus of zoosporangia or resting spores. Vegetative nuclear 

 divisions of the 'cruciform type.' Zoosporangia thin-walled, spherical, 

 ovoid, or slightly flattened by pressure, zoospores with one long and 

 one short flagellum. Resting spores spherical and with a slightly thick- 

 ened wall; aggregated in groups of eight, each group not enclosed in a 

 common membrane" (Couch, Leitner, and Whiffen, loc. cit.). 

 Parasitic in members of the Saprolegniaceae. 



KEY TO THE SPECIES OF OCTOMYXA 



Parasitic on Achlya glomerata O. achlyae, p. 782 



Parasitic on Brevilegnia sp., Geolcgnia inflata O. brevilegniae, p. 783 



Octomyxa achlyae Couch, Leitner, and Whiffen 



J. Elisha Mitchell Sci. Soc, 55:400, pis. 47-48. 1939 

 (Fig. 58 F-J, p. 778) 

 "Obligate parasite on Achlya glomerata Coker, causing spherical galls 

 mostly on ends of hyphae. Galls 50-1 50 jj. thick. Plasmodium at maturity 

 partially or completely filling the gall and segmenting into either zoo- 

 sporangia or resting spores. Zoosporangia globose to ovoid, thin-walled, 

 variable in size, 6 ^ to 16 jj. thick. Spores discharged through small 

 papillae which are formed only on some of the sporangia next to the 

 host wall, the other peripheral sporangia as well as those deeper within 

 the sorus discharging their spores through the peripheral ones; zoo- 

 spores biciliate with one long posterior and one short anterior flagellum, 

 6-14 in a zoosporangium. Resting spores smooth-walled, 2.4 jx to 3.2 [x, 

 aggregated in groups of eight. Sporangial and resting spore membranes 

 without cellulose as shown by a negative reaction with chlor-iodide of 

 zinc" (Couch, Leitner, and Whiffen, be. cit.). 



