THE ALG^-FUNGI (PHYCOMYCETES) 215 



Under magnification hyphse of bread mold are seen to con- 

 sist of heavy tubular cell walls in which the granular proto- 

 plasm is not separated by trans- 

 verse walls, as it is in most of 

 the algae. If the nuclei could 

 be seen, which is not possible 

 in unstained material, many of 

 them would be found within 

 the tubular hyphal wall. This 

 plant, therefore, is a coenocyte, 

 like the green alga VaucTieria 

 (Sect. 183). If Rhizopus pos- 

 sessed chlorophyll, it would re- 

 semble the vegetative structure 

 of Vaucheria. 



FIG. 176. Black mold 



Below is a slightly magnified illustration of plants, one of which has given rise 

 to the other by means of a runner, or stolon. Descending are the rhizoids and as- 

 cending are the aerial branches, upon the tips of which spores are borne within 

 sporangia. Above and at the right a more highly magnified sporangium is shown. 

 Its wall (w) incloses many spores (s), through which may be seen the columella 

 (c), which is the swollen tip of the stalk upon which the sporangium is borne. 

 This wall may be broken away, so as to leave some of the spores lying upon the 

 columella, as is seen in two cases of the plants shown below 



201. Bread mold: nutrition. Bread mold lives upon and 

 within its nutrient substance and absorbs food material directly 

 from it. Parts that are in contact with the substratum do the 



