124 MORPHOLOGY AND LIFE HISTORY 



that grow into the substratum (substance on which 

 the fungus grows), and over its surface. These 

 filaments constitute the mycelium. Compare their 

 diameter with that of the sporangiophores. Do 

 they appear to branch? 



' 6. Make a drawing, illustrating all points observed. 

 Make a diagram showing, in order, the relative 

 heights of six sporangia of various ages. Indicate 

 the scale used. 



D. Vegetative Propagation: 



1. If Rhizopus nigricans is used, study, with the naked 

 eye or hand lens, the formation of stolons by this 

 plant, and describe in full, with drawings, this proc- 

 ess of propagation. This plant (Rhizopus nigricans) 

 was at one time called Mucor stolonifer. Explain 

 the appropriateness of this latter specific name. 

 The generic name, Rhizopus (root-like foot), refers 

 to the branching mycelial hyphae, which form at the 

 tips of the stolons. Explain the significance of the 

 specific name nigricans (black). 



2. How does Phy corny ces nitens increase vegetatively? 



3. Study and draw stages in the germination of spores 

 that have been in sugar .solution for twenty-four 

 hours. (Use spores of Phy corny ces or Sporodinia, 

 as spores of Rhizopus do not germinate readily in 

 sugar solution.) 



E. Microscopic Characters of the Mycelium: 



1. Mount in water a small portion of the substratum 

 with the mold attached, and, if necessary, very 

 carefully tease it out with the needles. 



2. Study the mycelium. Is it branched? Are the 

 mycefial hyphae of the same diameter throughout? 

 Are cross- walls present? If so. describe their 

 frequency. 



