250 TEXT-BOOK OF FUNGI 



species the sporangiophores are simple and bear a single 

 sporangium at the tip, in others the sporangiophore is 

 more or less branched, and in some cases bears sporangia 

 of two distinct sizes and differing in other respects. Sexual 

 reproduction by the conjugation of two gametes, which are 

 sometimes of unequal size. Zygospores produced in the 

 substance of, or on the surface of, the matrix. 



KE Y TO THE SUB-FAMILIES 



A. Columella present. Mycelium stout, not anastomosing. 

 * Sporangium polysporous. 



Wall of sporangium heterogeneous, upper portion cuti- 

 cularised and persistent, basal zone deliquescent at 

 maturity. Piloboleae. 



Wall of sporangium homogeneous. Mucorineae. 



** Sporangium monosporous. Chactocladieae. 



B. Columella absent. Mycelium slender and anasto- 

 mosing. 



Sporangium globose. Morlierelleae. 



Sporangium cylindrical. Syncephalideae. 



Piloboleae 



These fungi grow on dung, and superficially resemble 

 species of Mucor^ from which Pilobolus is at once recog- 

 nised by the much-swollen apex of the sporophore, which 

 is usually beaded with drops of moisture. The swollen 

 apex of the sporophore or elongated stem is an arrange- 

 ment for suddenly projecting the small black sporangium 

 to a distance when mature. Many of these sporangia 



