972 



FUNG A CE^~PHYCOMYCETES 



CLASS I. PHYCOMYCETES De Bary, 1856. 



Definition. — Eumycetes with m3^celium continuous in the vege- 

 tative stage. 



Type Genus. — Mucor Micheh, 1729. 



Classification. — The Phycomycetes may be divided into subclasses 

 as follows : — 



A. Sexual spores when present isogamous (similar gametes) — Subclass i. 



Zygomycetes. 



B. Sexual spores when present heterogamous (dissimilar gametes)— 



Subclass 2, Oomycetes. 



ZYGOMYCETES. 



Definition. — Phycomycetes with similar gametes. 

 Classification. — The Zygomycetes may be divided into two 

 orders: — 



A, Several asexual spores in sporangia — Order i, Mucor ales. 



B. Solitary asexual spore, a true conidium, on conidiophore — Order 2, 



Entomophthorales. 



Only the first order is of interest to us. 



^ Order Mucorales. 



Definition. — Zygomycetes with several asexual spores in a 

 sporangium, which in some genera are conidia-like bodies. 

 Type Genus— Mi4cor Micheh, 1729. 



Classification.- — The Mucorales may be divided into the following 

 families: — 



A. Asexual spores in typical sporangia, in some genera few spored. 



I. Columella present, zygospores naked and thinly covered — Family 

 I, Mucoracecs. 



II. Columella absent, zygospores closely covered by hyphse — 

 Family 2, MortievellacecB. 



B. Asexual spores not in typical sporangia- — Families Choanephoracecs, 



ChcBtocladiacecB, PiptccladiacecB . 



Only the Mucoraceae are of importance to us. 



Family Mucorace^. ' 



These organisms have a ramified thallus, branches taking origin 

 laterally or by dichotomy. Some species are provided with rhizoids, 

 root -like hairs by which they are attached to the surface on which 

 they grow. From the surface of the mycelium some aerial branches 

 called ' gonidiophores ' take origin, each of which supports on its 

 distal extremity a pear-shaped, globular, or claviform sporangium 

 called gonidangium. The sporangium is at first separated from the 

 gonidiophore by a septum, which later protrudes into the lower 

 portion of the sporangium to form a variously shaped structure 

 termed the columella. 



Inside the sporangium or gonidangium endospores or gonidia 

 develop by free cell-formation. 



