6^ 



Plants and their Ways in Soiith Africa 



the buds in spring, that it is drawn away through little troughs 

 placed in holes bored into the trunk as far in as the new wood. 

 On a bright day a drop falls about once a second. Drop by 

 drop about twenty-five gallons of sap may flow from one tree 

 in a season, until the buds begin to unfold, and this will boil 

 down to about five pounds of sugar. 



How can we tell when a plant is making starch P 

 Place in a jar of water a plant which grows in water. The 



green silky thread-like plants in ponds 

 are suitable. In spring, leaf-bearing 

 plants may be obtained in some ponds 

 which should be used when possible. 

 Place the jar in the sun. In a few 

 minutes bubbles will rise from the 

 plant. Place the plants in water 

 which has been boiled. No bubbles 

 are given off. Boiling the water has 

 driven off a gas which the plants 

 need* in making starch. Breathe 

 through a glass tube into some boiled 

 water, and place the plants in this 

 water. Bubbles will soon begin to 

 come off. The carbon dioxide 

 that was breathed from the lungs is 

 required by the plant to combine 

 with water to make starch. 



What gas is given off when 

 starch is made ? Place a glass 

 funnel over the plants in the jar, with 

 the small end under water. Sink a test-tube into the water 

 obliquely, so that all the air may escape and the tube fill with 

 water. Without letting the open end come above water, place 

 it over the small end of the funnel. As the gas rises it drives 

 out the water. When the tube is full, light a long splinter, 

 and blow out the flame, leaving the coal glowing. Quickly 

 lift the tube from the water and thrust in the glowing splinter, 

 which again bursts into flame. We know from the last chapter 

 that oxygen is the gas necessary to light a fire. 



Fig. 71.— E, Elodea plants in 

 water, with the cut ends of the 

 stalks directed into the glass 

 funnel, F ; S, supports on which 

 the funnel rests ; T, test-tube ; 

 O, oxygen which has collected 

 in the test-tube. (From Far- 

 mer's " Practical Introduction 

 to the Study of Botany.") 



I 



