90 THE LOWER FUNGI— PHYCOMYCETES 



h". Mycelial threads 

 more definitely 

 tubular. 



10. Siphonaria, p. 95 



(2) Mycelium often wide-spreading, saprophytic; 

 resting spore in germination functioning as a 

 prosporangium, the swarmspores being delim- 

 ited in the extruded endospore. 



11. Rhizidium, p. 96 



b. Resting spores intramatrical. 



12. Dangeardia, p. 96 



2. Mj'celium not consisting of delicate threads. 



a. Mycelium consisting of a delicate stalk flattened at its 



tip to form a small disc which is either applied to or 

 developed in the host wall; sporangia long, fusiform, 

 proliferating. 



13. Harpochytrium, p. 96 



b. Mycelium not forming such a disc. 



(1) Re.sting spore endobiotic, germinating to form an 



epibiotic sporangium; mycelium consisting of a 

 short broad tube. 



14. Chytridium, p. 96 



(2) Resting spore epibiotic, germinating by 



swarmspores. 



(a) Contents of sporangium escaping into a 

 thin-walled vesicle in which the swarm- 

 spores are then formed; mycelium con- 

 sisting of a lobed or slightly divided 

 haustorivnn. 



15. Saccomyces, p. 98 



(6) Sporangium not extruding a vesicle; myce- 

 lium consisting of an unbranched fihform 

 or bladder-like haustorium. 



16. Phlyctidium, p. 98 



B. Sporangia and resting spores intramatrical, developing from a 

 swelling formed at the tip of the germ tube of the swarmspore. 



1. Sporangia and resting spores lacking a subsporangial vesicle. 



Resting spore wall smooth. 



17. Entophlyctis, p. 98 



2. Subsporangial vesicle present; resting spore wall spiny. 



18. Diplophlyctis, p. 98 



II. Only the tips of the branches of the mycelium intramatrical, entering 

 several host cells (polyphagus), parasitic. 

 A. Individual functioning as a sporangium or resting spore. 



1. Swarmspores freed from the sporangium through a definite 

 opening. 



19. Rhizophlyctis, p. 99 



