CHAPTER XIX 



PLANTS 



Properties of Living Matter. Living matter has quite 

 a complex chemical composition. It contains the ele- 

 ments nitrogen, carbon, hydrogen, oxygen, sulphur, 

 and phosphorus. Other elements are usually found in 

 living matter in minute quantities. The name protoplasm 



FIG. 270. Reproduction in a Strawberry Plant by Division. 



has been given to this complex combination of these ele- 

 ments. Life occurs only in protoplasm, and plants and 

 animals are largely composed of it. 



Protoplasm possesses the property of irritability and 

 responds to the stimuli of light, heat, and electricity. 

 Sprouts on tubers and plants in dark places always grow 

 toward the light. Leaves turn toward the source of 

 light. 



315 



