58 MORPHOLOGY AND CULTTIRE OF MICROORGANISMS 



all along the hyphae submerged in the substratum. At first both myce- 

 lium and conidia are colorless, later some or aU of the cells develop 

 heavy dark brown walls. Although not active as an agent of fermen- 

 tation, it occurs very frequently in the fermentation industries some- 

 times discoloring the fermenting products. The conidia bud out from 

 the cells of the mycelium in a manner resembling the yeasts. Its 

 occurrence with the yeasts has led to many careful descriptions of its 

 several types of spore production and its biological activities. 



SAPEOLEGNiACEiE AND ENTOMOPHTHORACE.ffi. — These are two 

 groups of Phycomycetes which differ from the mucors in habit and in 

 their prominent development of sexual reproduction. 



Entomogenous Fungi. — ^Numerous species have been identified as 

 the destroyers of particular insects. 



