MUCOB. 



201 



Mucor racemosus (Fig. 36), which occurs on bread and 

 decaying vegetable matter in very variable forms, has a 

 branched, multicellular sporangiophore, which may also attain 

 to a considerable height. Like M. Mucedo, the optimum 

 temperature ranges from 20-25 C. The brownish spor- 

 angia are developed at the ends of the branches. The spores 

 are colourless. Both the aerial and the submerged portions 

 of the mycelium are capable of forming transverse septa, 

 dividing the hyphse into a number of short cells. These are 



Fig. 36. Mucoi- racemoms. 1, Branched sporangiophore and sporangia (highly magnified); 

 2, hyphse with chlamydospores ; 3, branched mycelium ; gemma; formation. 



usually filled with protoplasm, and assume a spherical or 

 barrel shape ; this was first observed by Bail. They are 

 termed gemmae. The cells frequently form thickened cell- 

 walls, and store up reserve food material, thus constituting a 

 resting spore (chlamydospore). Both kinds of cells after 

 separating from the mycelium may again vegetate under 

 suitable conditions. 



When free access is given to atmospheric oxygen, both 

 spores and gemmae germinate and from an initial germinal 



