186 THE NATUBE AND WORK OF PLANTS 



remains unchanged. Repeat with the jar of dried 

 seeds. No effect is noticeable. Repeat with the ger- 

 minating seeds. The blaze is extinguished. Relight 

 and test again. The extinguishment of the blaze has 

 a double meaning. The oxygen of the air, which 

 is necessary to support the blaze, has been used by 

 the germinating seeds for their burning. In its 

 place is the carbon dioxide which has been produced, 

 which now forms one-fifth of the air in the jar. 



The burning of the quiescent dry seeds is so slow 

 that it has not produced any change in the ah" about 

 them. The second and third jars show that it is not 

 the influence of the jar which extinguishes the blaze. 



The above experiment may be performed with 

 mushrooms, flowers, or any portion of the living 

 plant which does not contain chlorophyl. Breath- 

 ing is carried on by all parts of the plant, but the 

 portions which contain chlorophyl take up the car- 

 bon dioxide thirty times faster than it is formed by 

 the same organ. Thus, if green plants were enclosed 

 in the jar the carbon dioxide would be quickly used, 

 and the amount of oxygen increased. 



226. Plants by day and hy night. — During the 

 daytime the green plant takes up thirty times as 



