36 The Living Plant 



comparable directly with those carried on by men, as the fol- 

 lowing table well shows. 



The Factory The Leaf, or other green structure. 



Rooms therein The cells. 



The power Sunlight, the red and blue rays. 



The machinery Chlorophyll. 



The raw materials Carbon dioxide and water. 



The manufactured product Grape Sugar. 



By-products Oxygen. 



The photosynthetic machinery can not only be apprehended, 

 but also represented in a mechanical plan, as our accompanying 

 diagram illustrates (figure 6). It represents the parts concerned 

 in the process, (shown simplified in figure B on Plate I,) reduced 

 each to a single one, and given a regular shape, though otherwise 

 constructed and related as in the plant. Later we shall consider 

 exactly the forces which keep the gases and liquids in motion 

 in the suitable directions. 



The reader should now be able to visualize, or see vividly in 

 imagination, this process in progress. Streaming in through the 

 stomata and along the air passages is a steady current of the tiny 

 particles, or molecules, of carbon dioxide, which reach the cell 

 walls, pass in solution through these and the protoplasm into the 

 chlorophyll grains, where they meet with water supplied in a 

 continuous stream by the ducts. Here in the grain the chloro- 

 phyll is stopping the red and blue light, and turning their vi- 

 brating waves against the molecules of the carbon dioxide in a 

 way to shatter that substance into its constituent atoms. The 

 carbon thus forced apart from its own oxygen is uniting with 

 the elements of the water into sugar, which is streaming into the 

 sap cavity and then away through the sieve tubes, while the dis- 

 carded oxygen is passing out from the grains through protoplasm 

 and wall to the air space, along which it is streaming to the 

 stomata and the outside world. And this is what is occurring 

 inside of all leaves through all the bright days of the summer. 



