MOLDS 51 



mucor fruits are produced only under special cultural conditions. 

 This organism is used in the amylo process of alcoholic fermentation. 



Fermentation activity has been described for numerous species of 

 Mucor and Rhizopus. Among them are Mucor circinelloides, Van 

 Tieghem, Mucor javanicus, Wehmer, Mucor plumbeus, Bonorden, 

 Rhizopus oryzce, Went, Rhizopus javanicus. The fermenting power 

 of mucors like that of yeasts varies greatly with the species or even 

 with races used, approaching in some species the efficiency of the 

 more active yeasts. 



THAMNIDIUM. Of related genera, Thamnidium differs from Mucor 

 in the production of two kinds of sporangia. The terminal sporangium 

 of a fruiting hypha resembles that of Mucor; the secondary or accessory 

 sporangia which are borne upon side branches of the sporangiophores 

 are smaller, lack the columella, and produce few to several spores 

 within an outer wall. 



Thamnidium elegans, Link, produces primary and secondary spor- 

 angia on different hyphae, together making white colonies. The fertile 

 side branches are produced in whorls and bear whorls of branchlets 

 from their centers which in turn produce sporangioles from the tips of 

 short straight twigs or branchlets. 



PENICILLIUM. The extremely abundant green molds . most fre- 

 quently belong to the genus Penicillium, although some members of 

 other groups may be confused with them at times. 



Characters. Colonies are composed of loosely woven hyphse, 

 branched, septate, colorless, or bright colored. The fertile hyphae 

 (conidiophores) are mostly erect, arising either from submerged hyphae, 

 or as branches of aerial hyphae, septate, usually branched only in the 

 fruiting portion. Conidial fructifications consist of more or less com- 

 plex systems of branches and branchlets, the ultimate fertile cells each 

 producing a chain of conidia (Fig. 34). The whole system is usually 

 grouped near the end of the conidiophore, giving the appearance of 

 one or more brooms or brushes (whence the name). Very few species 

 are known to produce asci, hence these are rarely encountered. The 

 conidial form continues for an indefinite number of generations, there- 

 fore all the activities of the genus are associated with this form. The 

 classification of the whole group, technically transferred by some 

 workers to the ascomycetes on account of certain forms, becomes 

 misleading, because it contains so few species producing asci. 



