114 



PLANTS WITHOUT CHLOROPHYLL 



Conclusion. — 1. What happens when fermentation takes place ? 



2. What gas is formed ? Explain fully. 



3. What substance is present in the flask? How do you know? 



TYIixtvxneof 



Yeast ^a Glucose '( Alcohol 



\Wa|tr. 



Apparatus to prove that Alcohol may be distilled from Fermenting 



Yeast. 



NOTE. — If we were to distill off the contents of the Erlenmeyer flask, we could 

 prove the presence of alcohol. Fermentation is the process which breaks up sugar 

 (C12H22O11) into carbon dioxide (CO2) and alcohol (C2H5OH). 



Problem, 91 : To learn to recognize yeast plants under the 

 compound microscope. 



Materials. — Compound microscope, nutrient solution con- 

 taining growing yeast plants from a compressed yeast cake (com- 

 posed of food and yeast plants), iodine. Lower figure, page 136, 

 Civic Biology. 



Method. — Place a drop of solution on a slide and add 

 iodine. 



Observations. — Note the dark blue bodies. What are they? 

 (Remember the iodine test.) The smaller ovoid bodies are the 

 yeast cells. What color are they? Shape? Do you find any 

 budding (one growing out from another cell)? Note the clear 

 areas {vacuoles) within the cells. 



Conclusion. — 1. Write a paragraph descriptive of yeast cells 

 and their method of reproduction. 



2. Draw a few cells showing budding. Add a starch grain for 

 comparison. Draw both to scale. 



