PLANT GROUPS 95 



a. Note the changes in the hyphpp produced after a longer 



period of growth. Are they branched or unbranched ? 

 unicellular or inulticellular ? Have they the same 

 structure as in the earlier stages noted above ? Is 

 the spore still visible ? Draw two or three of these 

 older stages in spore germination. Label correctly. 



b. Observe the mycelium of Jthizopus growing on bread or 



some other medium. How was this mycelium pro- 

 duced ? How related to the branched hyphse noted 

 above as a result of spore germination ? How do you 

 account for the origin of a mycelium on moist bread 

 or in a moist chamber upon which no spores are 

 artificially sown ? Is there a submerged mycelium 

 within the nutrient medium and an aerial portion 

 exposed to the air ? What is the function of the two 

 parts of the mycelium? See text and Fig. 140. 

 3. Nutrition. How does RJiizopus differ from apple mold in 

 the nature of its habitat ? Are the foods of its habitat 

 solid or liquid ? In the case of Rhizopus growing on 

 bread, how does the fungus absorb and use the starch 

 of the bread as food ? Contrast the nutrition of the 

 apple mold and that of Khizopu* growing on bread. 



REPRODUCTION 



1. Spore formation by sporangia. Observe a mycelium upon 

 which round balls, or sporangia, begin to appear (Fig. 139 

 of text). Place a patch of this mycelium with light- 

 colored sporangia on a slide and observe with a low 

 power without mounting. 



a. What is the relation of the sporangia to the hyphse ? 

 How are the sporangia related to the hyphte of the 

 mycelium ? Are they formed by any special hyphal 

 branches ? Consult the text and Fig. 140. 



