278 



It appears as a prominent, white growth on the surface of moist 

 bread, fruits arid vegetables. It causes the rotting of stored 

 fruits and vegetables. The mycelium is a branching, ccenocytic 

 filament which penetrates the food material and produces up- 

 right, aerial growths bearing sporangia. These sporangia bear 

 great numbers of spores which escape, become dry and sometimes 



FIG. 127. Rhizopus nigricans or bread mould; (a) entire plant showing sporangia; (6) 



mature zygospore. 



live for many years. They also reproduce sexually by the forma- 

 tion of processes which unite to form zygospores. 



The Ascomycetes contains the largest number of species of 

 any of the divisions of fungi and a great many of them are para- 

 sitic. It includes a great many species that are very destructive 

 to agricultural crops ; some molds that are used in making cheese, 

 which are of importance in the industries ; and some few that are 

 used for food. Many of the saprophytic species are of greater 

 importance than we realize as factors in the decay of organic 

 materials. They have two forms of reproduction the non-sex- 

 ual and the sexual. In the sexual method the spores are borne 



