CHAPTER II. 

 PLANT LIFE. 



By DR. ERNST A. BESSEY, 

 Department of Botany, Michigan State Agricultural College. 



SECTION VI. How PLANTS LIVE. 



Protoplasm. All living things possess certain 

 characteristics in common. If one studies plants and 

 animals he finds that the living substances of both are 

 practically alike. This living substance is called pro- 

 toplasm. It is more or less sticky or slimy and of 

 about the consistency of the white of an egg. It is this 

 that grows, that builds the framework, and performs 

 all the functions of life. 



Cells. Protoplasm is found in all the familiar ani- 

 mals and plants, not in one large mass, but in thou- 

 sands of little parts, microscopically small, called cells. 

 Each one of these has a thinner or thicker outer layer 

 to separate it from its neighbors and to give it strength. 

 In most animals some cells have thick walls and make 

 up the skeleton, while the rest of the cells are soft 

 walled and are to a large extent motile. In plants, 

 most of the cells have fairly firm walls, so that there 

 is no such chance for motility as in animals. 



Activities of Protoplasm. As long as the proto- 

 plasm is alive it is at work. One function that is pe- 

 culiar to protoplasm is the ability to manufacture new 

 protoplasm out of various substances which are not of 

 themselves alive. This new protoplasm is alive and 

 like that which produced it. Other activities of pro- 

 toplasm are the taking in and transformation of food 

 substances, manufacture of food in some cases, secre- 



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