PART I. LIVING THINGS IN RELATION TO THEIR 

 ENVIRONMENT AND TO EACH OTHER 



CHAPTER II 



THE ENVIRONMENT OF PLANTS AND ANIMALS 



Problems : ^ To discover some of the factors of the environment 

 of plants and animals. 



To discover the chemical nature of the environment, and of plants 

 and animals. 



Laboratory Suggestions ^ 



Demonstration. The composition of the air. 

 Demonstration. The separation of water into its elements. 

 Laboratory experiment. To determine the solubility of different sub- 

 stances. 



Demonstration. Oxidation of carbon and the test for carbon dioxide. 



Environment. — Each one of us, no matter where he lives, comes 

 in contact with certain surroundings. Air is everywhere around 

 us. Light and heat are necessary to us, so much so that we use 

 artificial hght at night and artificial heat in winter. Out of doors 

 we walk on the soil of a farm or a village, or on a city street, with 

 its dirty and hard paving stones. Water and food are a necessary 

 part of our surroundings. All these factors — air, light, heat, soil, 

 water, food, and other things — together make up our environment. 



But we must not think of the environment as simply the room 

 in which we sit, or the town in which we live. Sunlight, on which 

 our very existence depends, comes from the center of our solar 

 system, 93,000,000 miles away. The water which we use in our 

 kitchens may have been piped scores of miles to us : witness the 

 water supplies of Los Angeles and of New York. The food we use 



^ The Problems stated at the beginning of each chapter constitute, in a way, a key 

 to the text of the chapter. The Laboratory Suggestions are to be used at the dis- 

 cretion of the teacher. 



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