USE OF CHLOROPHYLL 



159 



the protoplasm of these cells are found a number of tiny green 

 bodies, the chloroplasts or chlorophyll bodies. If the leaf is 

 placed in wood alcohol, we find that the bodies still remain, but 

 that the color is extracted, going into the alcohol and giving to 

 it a beautiful green color. The chloroplasts are, indeed, simply 

 part of the protoplasm of the cell colored green. These bodies 

 are of the greatest importance directly to plants and indirectly to 

 animals. The chloroplasts, by means of the energy received from 

 the sun, manufacture 



air- 



airv 



sugars and then starch 

 out of certain raw ma- 

 terials obtained from the 

 soil and the air. These 

 raw materials are soil 

 water, which is passed 

 up from the roots through 

 the bundles of tubes into 

 the veins of the leaf, and 

 carbon dioxide from the 

 air, which is taken in 

 through the stomata or 

 pores. A plant with va- 

 riegated leaves, as the 

 tradescantia or " wander- 

 ing Jew," makes starch 

 only in the green part of the leaf, though these raw materials 

 reach all parts of the leaf. 



Changes in color in leaves. Green leaves are really solar engines 

 and like all machinery wear out after long usage. It has been 

 estimated that the total working life of a green leaf is about 1500 

 hours. In the fall we find leaves changing color, and we used to 

 think this was due to the action of frost. Now we think it is due 

 to the breaking down of the green coloring matter in the leaf. 

 This disintegration seems to be an oxidation process. As the 

 chlorophyll disappears from the leaves, the yellow color, which is 

 present in the leaf cells, can now be seen. But other autumn 

 colorations are not yet fully understood. 



Explain the difference in growth of the two plants. 



