CHAPTER I 

 WHAT IS BIOLOGY? 



Questions. 1. What does biology mean? 2. How is biology used? 

 3. What makes biology interesting ? 4. How is biology studied ? 5. What 

 is life ? 6. How do living things differ from other things ? 



1. Definition. The word biology is easily defined. It means 

 "life knowledge/' or "life teaching," from bios (life) and logos 

 (the word, or knowledge) . But, like many other simple words, it 

 covers a great deal of what people know, as well as much more 

 that they do not know. Many men have spent their lives in 

 trying to find out just what science, or real knowledge, is. Still, 

 we need not be afraid of the subject. Every one of us may 

 reasonably hope to get a considerable amount of reliable and 

 usable and satisfying knowledge concerning life. 



2. What is life ? Suppose you asked an expert electrician, like 

 Edison or Marconi, "What is electricity?" He would be likely 

 to answer very frankly, "I don't know." Yet everybody knows 

 something about how wonderfully electricity is controlled and 

 used. So we must say frankly we don't know just what life is, 

 although we have gathered many wonderful and important 

 jacts about life. These facts we are able to use in many ways. 



We give the name life to all that distinguishes living things 

 from those that are not living. Some people think that life is a 

 kind of force, or energy \ but if it is, it differs in many ways 

 from electricity and other forms of energy. Some people think 

 that life is a kind of substance, or fluid ; but if it is, it differs in 

 many ways from all the other kinds and states of matter that we 

 know. All we can say is (i) that life is present only in certain 

 objects or bodies {plants and animals), which contain many 

 different kinds and states of matter; and (2) that in these 



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