CHAPTER III 

 THE GROWING PLANT 



HAVING now taken the plantlet out of th'e seed and hav- 

 ing established it as an independent organism, we may 

 next inquire how it secures its food and how it grows. 



57. Chlorophyll. Soon after the plantlet emerges 

 from the seed-case, a green color appears in the parts 

 most exposed to light. This is due to the formation within 

 the cells of chlorophyll the green coloring matter of 

 plants. Chlorophyll forms only in light, and when a 

 plant containing green leaves is kept for a time in the 

 dark, as when celery is banked up with earth, the chloro- 

 phyll disappears and the green parts become white. The 

 chlorophyll saturates definite particles of protoplasm, 

 called chlorophyll bodies, and since the cell-walls and 

 protoplasm are transparent in the younger cells, the 

 chlorophyll bodies give the parts containing them a green 

 color. Fig. 15 shows the distribution of the chlorophyll 

 bodies in the cells of a portion of a leaf of the beech. They 

 appear as minute globules, which in this case are mostly 

 located near the cell-walls. They are most numerous 

 near the upper surface of the leaf < the part most exposed 

 to the sun's rays. 



58. Formation of food. No food can be formed with- 

 out chlorophyll. By the agency of chlorophyll, the 



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