CHAPTER VIII 



ORGANIC RESPONSE 



Environment. Except in abstract thought, a 

 living organism cannot be dissociated from the rest 

 of the universe of which it forms a part. This 

 " rest " we call the environment. It includes all 

 external matter, the presence or absence of which, 

 or the alteration of which, produces any sort of a 

 change in the organism itself. The spatial limits 

 included under the term environment are wholly 

 relative. Thus, the soil-environment of a tree is 

 very limited in extent, whereas the sun, in spite of its 

 very great distance from the earth, forms a very 

 essential part of its environment as well as that of all 

 living forms. The community in which a man lives 

 forms a significant part of his organic environment, 

 since the presence or absence of other people affects 

 and conditions his own actions. A few centuries 

 ago such a social environment would have been very 

 limited in extent on account of the isolation of com- 

 munities. Nowadays, thanks to telegraph and 

 newspaper, human activities in any part of the world 

 may alter or affect the actions of any one ; hence this 

 sort of environment has greatly extended. 



In a more limited sense, however, we usually 

 apply the term environment to an organism's immedi- 



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