Nutrition. 



93 



should be bent at right angles, and a match wedged in it, with 

 i or 2 centimeters of the tip exposed, and the head in contact 

 with the sanded paper. 

 When all is in readiness, 

 lift the bell jar, set the 

 candle burning, and re- 

 place. Arrange the rod 

 bearing the match in 

 the manner described. 

 Seal all joints with 

 vaseline. After a min- 

 ute or two the candle 

 will have used so much 

 of the oxygen, and given 

 off so much carbon 

 dioxide, that combustion 

 is impossible, and the 

 flame is extinguished. 

 Allow the preparation 

 to stand in the light 

 for several hours. Pull 

 the glass rod upward 

 through the cork, draw- 

 ing the match-head 

 along the sanded paper. 

 After igniting the 

 match, twist the ro,d, 

 and place the flame in 

 contact with the wick. 

 The relighting of the 



Candle denotes that Fig- ^-Preparation for testing relations of 



plant to atmosphere. A, candle; B, match; 



the Carbon dioxide Of C, strip of sanded paper on wooden support ; 



the air has been ab- D ' 1 &lass rod holdin f match: the dotted line 

 shows position when the match is applied to 



sorbed by the plant, the candle. 



