76 THE PLANT: A GENERAL INTERNAL VIEW 



Fig. 27. — Turgid cells of a very sim- 



plant cells. When you understand what is known of 

 these life processes in one plant cell, you understand what 

 is known of them in all plant cells. Thus the living cells 

 are the plant's stomach, its lungs, and its heart, in so far 



as a plant has stomach, and 

 lungs, and heart. In truth, of 

 course, the plant has no such 

 organs, yet what those organs 

 do for you must also be done 

 in some manner by a plant. 

 Though the plant does not 

 have the same organs that 

 animals have, it does have the 

 same general functions to ac- 

 complish. Digestion and res- 

 pie, one-celled plant as seen under piration are examples of these 

 a microscope. functions. You have learned 



of them in your study of physiology. In plants these 

 functions are accomplished by each cell for itself. 



All this about the internal structure of plants, about 

 cells and protoplasm and the work they do, may not 

 interest you, for it is about things with which you are 

 not familiar and cannot see with your naked eyes. In 

 order to make it interesting, you need to use your imagina- 

 tion. There is need for imagination in connection with the 

 study of science as well as in the study of anything else. 

 For the sake of this lesson it is perhaps a pity that a plant 

 cell is not as big as a tree and as common as a tree in your 

 experience. In importance it is certainly as big as a tree, 

 and you cannot begin to understand a tree until you begin 

 to understand the cells which compose it. Your mind can 

 readily picture a tree. Similarly, let it picture a plant cell, 



