114 MICRO-ORGANISMS AND FERMENTATION. 



main branches (b) send out short, root-like, branches with 

 frequent forking (c) ; at the base of these come new mycelial 

 branches (V), which grow 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 dis- 

 tinguished by the columella being studded on its uppermost 

 part with pointed, thorn-like protuberances, the mycelium, 

 when submerged in a saccharine liquid, produces gemmae, 

 similar in formation to those of Mucor racemosus and Mucor 

 erectus. 



Mucor stolonifer (JRhizopus nigricans) attains a considerable 

 size, and occurs very commonly, for instance, on succulent 

 fruits. This mould is easily recognised, for its brownish- 

 yellow mycelium sends out, diagonally, thick hyphse without 

 septa. These attain a length of about 1 cm., then, sinking 

 their points to the surface of the substratum, send out line 

 ramified hyphse, resembling rootlets, into the latter, whilst 

 other hyphse rise perpendicularly and develop sporangia ; 

 other branches again form new " runners." The black 

 sporangium possesses a high, dome-shaped columella, and 

 develops a number of dark-brown spores, round or angular. 

 When these are freed by the absorption of the sporangium 

 wall, the columella curves over on the sporangium-carrier like 

 an umbrella, the line of junction of the external wall remaining 

 in evidence in the form of a collar. In this species no for- 

 mation of gemmae has been observed. 



The species of Mucor have very considerable interest from 

 one point of view, since they are able to act, in different 

 degrees, as true alcoholic ferments. Their fermentative power 

 is not related exclusively to their power of forming budding 

 gemmae, since these have not been observed in Mucor Mucedo 

 and stolonifer. 



According to HANSEN'S investigations, the various species, 

 as far as they really are alcoholic ferments, induce fer- 

 mentation not only in solutions of dextrose and invert-sugar, 

 but also in solutions of maltose. Of all the species which he 

 investigated, Mucor racemosus is the only one capable of inverting 



