278 



COLLEGE BOTANY 



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

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

 fruits and vegetables. The mycelium is a branching, coenoeytic 

 filament which penetrates, the food material and produces up- 

 right, aerial gi-o-wths bearing sporangia. These sporangia bear 

 great numbers of spores which escape, become dry and sometimes 



Fig. 127. — Khizopus nigricans or bread mould; (a) entire plant showing sporangia; (b) 



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. ~Manj of the saprophytic species are of greater 

 importance than we realize as factors in the decay of orgaaic 

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

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



