The Mucoraceæ, in addition to the chlamydospores and oidia, have a more normal and ordinary method of reproduction; viz., by _spores_ which are formed without any sexual act. _Mucor_ has round sporangia; from the mycelium one or more long branches, sometimes several centimetres in length, grow vertically into the air; the apex swells (Figs. 78, 80) into a sphere which soon becomes separated from its stalk by a transverse wall; in the interior of this sphere (sporangium) a number of spores are formed which eventually are set free by the rupture of the wall. The transverse wall protrudes into the sporangium and forms the well-known columella (Fig. 80 _d_, _e_). The formation of spores takes place in various ways among the different genera. [Illustration: FIG. 79.--Chlamydospores of _Chlamydomucor racemosus_ (× 375 times.)] [Illustration: FIG. 80.--_Mucor mucedo_: _a_ a spore commencing to germinate (× 300 times); _b_ a germinating spore which has formed a germ-tube from each end (× 300 times); _c_ the apex of a young sporangium before the formation of spores has commenced; the stalk is protruded in the sporangium in the form of a column: on the wall of the sporangium is found a very fine incrustation of lime in the form of thorn-like projections; _d_ a sporangium in which the formation of spores has commenced; _e_ a sporangium, the wall of which is ruptured, leaving a remnant attached to the base of the columella as a small collar. A few spores are seen still adhering to the columella.] SEXUAL REPRODUCTION by conjugation takes place in the following manner. The ends of two hyphæ meet (Fig. 81) and become more or less club-shaped; the ends of each of these are cut off by a cell-wall, and two new small cells (Fig. 81 _A_) are thus formed, these coalesce and give rise to a new cell which becomes the very thick-walled zygote (zygospore), and germinates after period of rest, producing a new hypha, which bears a sporangium (Fig. 81 _E_). _Mucor mucedo_, Pin-mould, resembles somewhat in appearance _Penicillium crustaceum_ and is found growing upon various organic materials (bread, jam, dung, etc.). _Pilobolus_ (Figs. 83, 84) grows on manure. Its sporangium (Fig. 84 _a″_) is formed during the night and by a peculiar mechanism (page 92) is shot away from the plant in the course of the day. This generally takes place in the summer, between eight and ten a.m. The sporangium is shot away to a height which may be 300 times greater than that of the plant itself, and by its stickiness it becomes attached to portions of plants, etc., which are in the vicinity. If these are eaten by animals, the spores pass into the alimentary canal and are later on, sometimes even in a germinating condition, passed out with the excrement, in which they form new mycelia. _Phycomyces nitens_ (“Oil-mould”) is the largest of the Mould Fungi; its sporangiophores may attain the height of 10–30 c.m.