36 



FUNCTIONS OF A GREEN CELL 



observed. This is called the Brownian motion. Modern physics 

 teaches that molecules move not only in solution and during 

 osmosis, but that the molecules of all matter are constantly bom- 

 barding each other. The desk on which you write is composed 

 of tiny particles not inseparably cohering and sticking to each 

 other, but in a slight, constant state of activity similar to that 

 which you observed in the particles under the microscope. 



Food manufacture. A green cell is one containing certain organ- 

 ized and specialized cytoplasm, called chloroplasts. There is 

 found in these chloroplasts a complex, green material, chlorophyll, 

 which is necessary for the manufacture of food. The green cell is 

 independent because it does not rely on other organisms for its 

 food ; it manufactures its own. All cells, whether green or not, need 

 carbohydrates (sugar and starches), fat, and protein. The cells 

 manufacturing foods always absorb two compounds : a gas, carbon 

 dioxide (CO2), and water (H 2 O). These raw materials get through 



There is a continuous income and outgo of gases during respiration and photosynthesis. 



the cell wall and plasma membrane by the process of osmosis. 

 Then the chloroplasts by a number of complicated processes, with 

 the aid of sunlight, chemically tear apart the elements of these 

 compounds, water and carbon dioxide, and recombine them into 

 simple carbohydrates. Since more oxygen is contained in the raw 

 materials than in the sugar manufactured, oxygen is given off 

 during the process. It is supposed by some that the elements 



