CHAPTER 14 • HOW DO LIVING THINGS ADJUST THEMSELVES? 



1 Are there any conditions in which Hving things are perfectly 



adapted ? 



2 Do all Hving things make mistakes? 



3 How do living things fit themselves to new conditions? 



4 Do all living things learn from experience? 



5 Do plants learn in the same way as animals do? 



6 Do other animals learn in the same way as human beings do? 



7 Does the adaptation of a living thing carry over to later genera- 



tions ? 



8 Can human nature be changed? 



9 Can the nature of other species be changed? 



Living means doing, acting. We cannot think of life existing as a pebble 

 on the beach exists, or as a gold brick in a vault. Life is a system of proc- 

 esses. It is related, in one direction, to meeting outside conditions; but it is 

 related, in another direction, to keeping itself going. Life persists through 

 the changes that it brings about. 



And yet, only to a certain point. The environment in which, and in rela- 

 tion to which, a particular plant or animal lives is itself a changing system. 

 The light changes. The temperature changes. Water vapor and other sub- 

 stances vary in amount. Other living things, also in action, interfere, injure, 

 destroy, although still others furnish food. Plants and animals become 

 diseased. They are poisoned, starved, suffocated. They make mistakes. 



How do living things meet new situations? How do they change 

 through experience? 



How Do Plants Respond to Changes? 



Response to Short Season A crop of wheat in the extreme north, as 

 in Canada or Alaska, will ripen in, say, about ninety days after the sowing. 

 In a more temperate climate the same strain will take four months or more 

 to ripen. The adjustment of the plant to the shorter season is very impres- 

 sive. How can the plant tell that the frost is going to come earlier in 

 Manitoba than in Oklahoma? Perhaps this adjustment is easier to under- 

 stand if we attend to the actual facts. 



In any given species, such as a particular strain of wheat, developing 

 from the seed to the ripe grain requires a certain amount of nourishment. 

 But this in turn depends upon a certain amount of sunshine. From our 

 knowledge of the earth and its movements, we can understand that one 

 hundred days in the short season of a northern region have, on the average, 



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