BOTANY. 



103 



third (No. 3) upside down over a tumbler of water 

 with some of the leaves in the water, but the root 

 exposed. In due time No. i will have faded ; No. 2 

 will be quite fresh ; No. 3 will have the parts not in 

 the water faded. No. i shows that water contained 

 in the plant has evaporated from its surfaces ; No. 2 

 that the water has been absorbed by the root and 

 conveyed to the leaves ; No. 3 that the immersed 

 leaves have not supplied the emerged portion of the 

 plant with water. 



157. Decomposition of the carbonic acid of 

 the air by plants in sunlight. Take a bunch of 



FIG. 68 



fresh green leaves water-cresses answer well and 

 place them in a large bottle, then fill the bottle quite 

 full of fresh spring water, so that no bubble of air is 

 left in the bottle. Turn the mouth of the bottle, full 

 of water and leaves, downwards into a basin full of 

 water, and place the bottle and basin in the strong 

 sunlight for an hour or two. If the leaves be then 

 carefully examined they will be found to be covered 

 with small bubbles, and that more of these bubbles 



