CHAPTER XXII 

 PROTOPLASM 



No living thing plant, animal or man is wholly alive. 

 In each and all there is some lifeless matter. Only a part 

 of the matter in a wonderful towering tree, for example, 

 is live matter. But it is that live part which makes the 

 tree grow and take on beauty of form and structure. 



Just as matter is composed of molecules, so we may 

 think of the living parts of our bodies as made up of 

 countless millions of cells. It is the growth of these cells 

 and the formation of new ones from them that enable our 

 bodies to increase in size and to repair the wastes of use. 



The material of which all these cells are made is called 

 protoplasm. To understand ourselves and all living things 

 around us we must know about this protoplasm. 



All living things have certain activities without which they 

 cannot exist. These activities are known as functions, or life 

 processes, and they are carried on by some organ or organs of the 

 living thing, or organism. 



The functions, or life processes, are sensation, motion, respira- 

 tion, food-taking, digestion, absorption, circulation, assimilation, 

 excretion and reproduction. They are not only activities of man 

 but are also activities of all living animals. Plants have simi- 

 lar activities. In addition, plants perform a function not pos- 

 sible for other living things. They not only take food and use 

 it as man and animals do, but green plants actually manufacture 

 food. Without this work of the green leafy plants there would be 

 no food, and all life on the globe would perish. 



Man, animals, and plants are also alike in composition. Their 

 living parts consist of protoplasm. Protos means first and plasma 

 means form ; so protoplasm means the original simple form of 

 substance of which living things are made. 



When examined under the compound microscope, protoplasm 

 appears to be a thin, granular, nearly transparent fluid. Although 



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