PHYSICS AND CHEMISTRY AND LIFE 117 



brown, and the corn in the fields " fires," as the farmers 

 say. 



So far as plants are concerned, evaporation appears to be 

 a hindrance as well as a help. Plants can stand heat 

 better then we can, but they cannot stand loss of water 

 so well. It is easier for us to take a drink than it is for 

 them to get more water. Plants which' live in dry places, 

 as in deserts, are mostly plants whose construction protects 

 them against evaporation. Their power to retain water is 

 much greater than that of plants which live in regions 

 where water is more abundant. (See page 51.) 



39. Physics and Chemistry and Life. The matters we 

 have been considering in this chapter belong in those 

 divisions of science called physics and chemistry rather 

 than in that division of science called botany. Such mat- 

 ters are studied by botanists only as they relate to plant 

 life, and it is in this way that you have been studying 

 them. In physics and chemistry they are studied for 

 their own sake; not in order to understand life, but in 

 order to understand the behavior of matter and energy 

 whether in living things or in non-living things. Botany 

 is science as related to plants. Physics and chemistry are 

 science as related to matter and energy. 



Nature, however, does not recognize these divisions of 

 science which men have made. All her forces work to- 

 gether. You cannot study the life forces without also 

 studying the other forces. You cannot tell where the 

 " other " forces stop and the life forces begin. They are 

 a part of the living world as well as a part of the non- 

 living world. Life obeys them, and they serve life. This 

 you have already seen. 



