CHYTRIDIALES 581 



resting spores; zoosporangium operculate, generally apophysate, intra- 

 or extramatrical, internally proliferous; zoospores posteriorly uniflagel- 

 late, with a single globule, escaping through a sessile pore or a discharge 

 tube, generally undergoing a period of rest at the orifice before swim- 

 ming away; resting spore borne like the sporangium, thick-walled, 

 germination not observed. 



A genus containing species saprophytic in the decaying parts of higher 

 plants and in the gelatinous sheath of Chaetophora. 



The vegetative system is ordinarily very extensive and profusely 

 branched and bears numerous irregularities. It may be entirely within the 

 substratum or, more often, form an extensive extramatrical growth. 

 The commonest species, N. elegans, may generally be collected by 

 baiting aquatic sites, or even water cultures containing vegetable trash, 

 with bits of grass or corn stem. 



KEY TO THE SPECIES OF NOWAKOWSKIELLA 



Sporangia and vegetative swellings smooth-walled 



Zoospores less than 10 \± in diameter; operculum always external 

 Sporangia spherical, subspherical, oval, ovoid, ellipsoidal or 

 pyriform; rhizoidal system highly variable in diameter, 

 branching, and extent 

 Resting spore borne in a one-celled container 



Rhizoidal swellings usually not septate, never pseudoparen- 

 chymatous; resting spore where known smooth-walled 



N. elegans, p. 582 



Rhizoidal swellings frequently forming variously oriented 

 cross walls and becoming pseudoparenchymatous; rest- 

 ing spores with low verrucae, occasionally smooth- 

 walled A', ramosa, p. 586 



Resting spore typically formed in the upper half of a two-celled 



container from the fused contents of the two halves 



N. hemisphaerospora, p. 587 



Sporangia predominantly cylindrical or clavate, borne on a once- 



or several-septate stalk N. elongata, p. 588 



Zoospores more than 10 [jl in diameter; operculum slightly sunken 



in discharge tube or external N. macrospora, p. 589 



Sporangia and turbinate cells bearing setae N. atkinsii, p. 591 



