CLASS III. PHYCOMYCETES
The Phycomycetes, which are characterized by the mycelium being continuous and nonseptate, in the vegetative stage, contain several families, one of which, Mucoraceae, has organisms parasitic of man. The fungi belonging to this family have a branching mycelium with aerial branches (gonidiophores), each of which suports on its distal extremity a globular, pear-shaped or claviform sporangium, called gonidangium, which is at first separated from the gonidophore by a septum. This septum later protrudes into the lower portion of the sporangium and forms a variously shaped structure known as columella. By free cell formation, gonidia develop inside the sporangium. The sporangial protoplasm not used in the formation of the gonidia is transformed into a peculiar mucillaginous substance, which later dries up and is the cause of the sporangium bursting. Each gonidium which becomes free gives rise by germination to a mycelial filament. There is also at times a