PROBLEM 90 113 



NOTE. — Some of these threads roach down into the bread and act as roots, di- 

 gesting and absorbing nourishment. These are called rhizoids. Many of the 

 hyphae are prolonged into tiny upright threads, bearing at the top a little ball. This 

 is called the sporangium. 



With the low power of the microscope the structure of a 

 sporangium may be made out. The dark-colored ones are full 

 of ripe spores, which may be seen by lightly tapping the cover 

 slip over the slide. How do the spores get out of the sporan- 

 gium ? Try to find some young sporangia and note the differences 

 in size and color between them and the older ones. 



Conclusion. — 1. How does bread mold get its food? 



2. How do you know that it cannot manufacture its own food ? 

 Explain. 



3. Have you seen any other kinds of molds on foods? If so, 

 on what foods? 



4. What effect do molds have on food ? 



5. What are the spores on bread mold for? 



6. What effect do their size and numbers have on the spread of 

 the mold? 



Drawings. — Draw a series of sporangia as seen under the low 

 power. 



Problem, 90: What is fermentation and what causes it ? 



Materials. — Fermentation tube, yeast, molasses, test tube, 

 Erlenmeyer flask, limewater, absorbent cotton, cork, and delivery 

 tube. 



Method. — Carefully fill a fermentation tube with a mixture of 

 molasses, water, and a little piece of compressed yeast cake. Plug 

 the open end with absorbent cotton. Put in a warm place over 

 night. Partly fill an Erlenmeyer flask with a mixture of molasses, 

 water, and compressed yeast cake. Close the flask with a stopper 

 fitted with a delivery tube which leads into a test tube filled with 

 limewater. 



Observations. — What has happened to the filled end of the 

 fermentation tube? How do you account for this? Smell the 

 contents of the flask after a day or two. What is this odor? 

 What has happened to the limewater? 



HUNTER LAB. PROB. 8 



