THE MOULD-FUNGI. 97 



able height. The brownish sporangia are developed at the 

 ends of the branches. The spores are colourless. When 

 this fungus is cultivated in wort, the submerged mycelium 

 swells irregularly, and a large number of transverse septa 

 appear, which divide it into large barrel-shaped or irregular 

 cells filled with highly refractive plasma. These cells gemmce 

 are readily separated, and then assume a spherical shape 

 (compare Fig. 21,7), as was first observed by Bail, and multi- 

 ply by budding like the true yeast-fungi ; the same takes 

 place with the submerged spores (Mucor-yeast, spherical 

 yeast). The mycelium produces a similar characteristic for- 

 mation of gemmae when cultivated on solid substrata. The 

 plasma of the filaments collects in certain places in a 

 compact mass, and is then enclosed at both ends by a 

 transverse wall. At the same time the cell swells, the, walls 

 become thickened, and fatty substances are stored in the 

 interior. The intermediate portions of the hyphae gradually 

 lose their contents. 



Mucor erectus occurs, for example, on decaying pota- 

 toes and has the same microscopic appearance as Mucor 

 racemosus ; physiologically, however, it differs from this. 



Mucor circinelloides (Fig. 21) has a very characteristic 

 appearance. The mycelium (1) shows the remarkable 

 branching which occurs in some of the species of Mucor : 

 the main branches (6) send out short, root-like, repeatedly- 

 forked branches (c) ; at the base of these grow new mycelial 

 branches (r), which become erect, and are able to form 

 sporangia (2 to 5) ; the sporangium-carrier is branched. 

 During its development it becomes considerably curved, and 

 to this the species owes its name of circinelloides. In 

 this form, as in Mucor spinosus, whose chocolate-brown 

 sporangia are distinguished by the columella being studded 

 on its uppermost part with pointed, thorn-like protuberances, 

 the mycelium, when submerged in a saccharine liquid, 

 produces a similar formation of gemmae, as Mucor racemosus 

 and Mucor erectus. 



H 



