CHYTRIDIACEAE 



33 



(s) Zoospores encysting at ori- 

 fice; in pollen-grains of 

 Typha 

 n. Orifice basal or subbasal 

 (m) Sporangia spiny 

 (n) Sporangia smooth 



r. Hyphae drawn out to extremely 



slender tips 

 s. Hyphae more or less tubular 

 y. Sporangia without a basal vesicle 

 (b) Mycelium often polyphagous; resting 

 spore serving as a prosporangium, the 

 zoospores forming in the extruded 

 endospore 

 b. Mycelium not consisting of delicate threads 



(1) Mycelium a delicate stalk with disk-like 



tip applied to or formed in the wall of 

 host; sporangia long, fusiform, pro- 

 liferating; algicole 



(2) Mycelium without such a disk 



(a) Resting spores endobiotic, germinating 



to form an epibiotic sporangium; 

 mycelium a short broad tube; algicole 



(b) Resting spores epibiotic, germinating 



by zoospores 

 X. Sporangia extruding a vesicle in which 

 the zoospores develop; mycelium a 

 lobed haustorium; in Euglena 

 y. Sporangia not extruding a vesicle; 

 mycelium a filiform or inflated haus- 

 torium 

 2. Sporangia and resting spores intramatrical, 

 formed from a swelling at the tip of the germ- 

 tube of the zoospore 



a. Sporangia with a basal vesicle; resting spore 



spiny; in Characeae 



b. Sporangia without basal vesicle; resting spore 



smooth; algicole 

 B. Mycelium intramatrical only at the tips, polyph- 

 agous, parasitic 

 1. Individual functioning as a sporangium or rest- 

 ing spore 



a. Sporangia with a definite orifice; algicole 



b. Sporangia without orifice, the wall breaking 



to emit the zoospores in a rotating sphere; 



in Hormotheca 

 2. Individual functioning as a prosporangium, ex- 

 truding a vesicle in which the zoospores are 

 formed; resting spores produced by copula- 

 tion 



a. Zoospores ciliate, escaping before germina- 



tion; in Euglena and Chlamydomonas 



b. Zoospores not ciliate, germinating in the 



sporangia; on Draparnaldia 



Achlyella 94 

 Asterophlyctis 94 



Rhizoclosmatium 94 

 Siphonaria 95 

 Rhizophidium 91; 1 



Rhizidium 96; 1 



Harpochytrium 96 



Chytridium 96; 1 



Saccomyces p. 98 

 Phlyctidium 98 



Diplophlyctis 98 

 Entophlyctis 98 



Rhizophlyctis 99 

 Nowakowskia 99 



Polyphagus 100; 1 

 Sporophlyctis 100 



