LIFE HISTORIES OE FUNGI 267 



( — ) value, which fuse and form a zygospore. Such 

 mycelia are, of course, monoecious. 



The hfe-cycle of a dioecious mold is illustrated in 

 Fig. 192. 



258. 'Phycoia.ycetes.-^Rhizopus nigricans represents the 

 group of Phycomycetes, lower fungi, often called "tube- 

 fungi." The group is characterized by the tubular hyphae 

 without septa. In this coenocytic character they re- 

 semble the filamentous or tubular green algse (such as 

 Vaucheria, or "green felt"), of which they are supposed 

 to be degenerate descendants. 



259. Life-cycle of Rhizopus. — The life-cycle olRhizopus 

 may be diagrammed as follows : 



OUTLINE OF LIFE HISTORY OF RHIZOPUS 



(-H) Spore (— ) Spore 



i i 



Mycelium Mycelium 



I i 



Gametangium Gametangium 



i i 



(-I-) Gamete ( — ) Gamete 



Conjugation 



Zygospore 



Germ-tube 



i i 



Sporangium 



i 



{-[-) Spores (— ) 



i i 



(-I-) Mycelium ( — ) Mycelium 



i i 



Sporangium Sporangium 



i i 



(-(-) Spore ( — ) Spore 



