RESPIRATION AERATION FERMENTATION 227 



Place a glass bell jar with an opening at the top in each. Put fresh active 

 green shoots into A and B. Put a burning candle (2 or 3 inches high) 

 supported by corks; under each jar. Pour water into the dishes until it 

 rises 2 or 3 inches. Put corks into the tops of the jars and note the effect 

 on the flames. Explain, tover jar B with a heavy black cloth and set all 

 three in strong sunlight for three hours. Lower a lighted taper into each 

 and note the effect. Explain. 



Exercise 4- Put 10 per cent, sugar solution of glucose, sucrose, and 

 lactose each into two fermentation tubes as directed by the laboratory 

 instructor. Put a fragment of good yeast into each, plug with cotton and 

 set aside for twenty-four hours. Test those showing gas by inserting a 

 stick of caustic potash. Explain. 



Exercise 5. Pour 500 c.c. of modified Pasteur's * solution into a one- 

 liter Erlenmyer flask ; add two grams of good yeast. Close the flask with 

 a cork carrying the short arm of a bent glass tube, the long arm so bent 

 as to reach a wash bottle. Allow the fermentation to drive out the air- 

 then insert the long arm into a bottle of baryta water. Note the effect 

 and explain. 



Allow the flask to stand for a week so as to permit complete fermenta- 

 tion. Test a small amount of the liquid for glucose. 



Exercise 6. Add yeast to a 4 per cent. : sugar solution. Examine in 24 

 hours and note the formation of gas. Test for sugar. 



* Water 500 c.c. 



Glucose 75 grams 



Ammonium tartrate 5 grams 



Potassium di-hydrogen phosphate 1 gram 



Calcium chloride 5 gram 



Magnesium sulfate 5 gram 



