CLASSIFICATION OF THE MOLDS 61 



>ne of the species of Mucor, Mucor rouxii, like the species 

 of Ehizopus above mentioned, has been used in the sacchari- 

 fication of starch. Some of the species produce heavy- 

 walled resting cells or chlamydospores in the vegetative 

 mycelium. This is particularly true of Mucor racemosus. 



Oospora. This genus is sometimes known as Oidium. 

 Tne most common species is Oospora lactis, a mold very com- 

 mon upon sour milk and cheese; in fact, it is to this mold 

 that many types of cheese owe in part their characteristic 

 flavor and aroma. The mycelium of this fungus grows very 

 largely below tfnTsurface of the medium on which it is de- 

 veloping, and later splits up by transverse fission into nu- 

 merous spores or oidia. These spores frequently do not 

 stand out upon the surface of the medium but are developed 

 below. No distinct conidiophores are formed. The myce- 

 lium shows a characteristic type of branching. Instead of 

 having main shoots with side branches, the terminal cells 

 usually divide and two branches of equal size develop from 

 tijx_ This type of branching is termed dichotomous. 



Aspergillus. The spores of Aspergillus are relatively 

 common in the air. The organism grows on all sorts of 

 decaying vegetation, on moldy corn, grain, bread, etc. In 

 color it is usually greenish, yellow, orange, black or brown. 

 The mold has generally a velvety or powdery appearance. 

 The hyphae are much branched and septate. The fertile 

 hyphae grow out into the air, the tip becoming enlarged 

 or club-shaped. From this enlarged tip are developed 

 numerous small branches called sterigmata. These usually 



F. Sporangium gray, yellow M. erectus. 



FF. Sporangium black M. fragilis. 



DD. Branches of sporangiophore nearly 



equal, .cymose. 



E. Sporangia borne irregularly M. ambiguus. 



EE. Sporangia in two rows, alter- 

 nating. 



F. Spores spherical to short ellip- 

 soidal M . circinelloides. 



FF. Spores longer, ellipsoidal M. alternans. 



