CHAPTER V. 

 Instinct and Sense-Experience. 



J NSTINCTIVE actions are not absolutely uniform 

 and infallible. On the contrary, they may be mod- 

 ified by experience. Ants kept in artificial nests 

 generally fall with fury upon any strange object intro- 

 duced into their midst. But this behavior may be 

 modified. If a piece of ice is thrown among them, 

 they first attack it violently. Soon, however, they 

 experience the fatal cold and retreat, taking sooner or 

 later a "lesson" for the future. The question is 

 whether this element of experience changes the nature 

 of an instinctive action and elevates it to the rank of 

 such as proceed from intelligence. 



As we have indicated, it is the general opinion of 

 modern naturalists, that only those actions of animals 

 are instinctive which immediately arise from heredi- 

 tary disposition, whilst all those which pre -suppose 

 individual experience are due to intelligence. 



Mr. George W. Peckham of Milwaukee, who has 

 written some interesting papers on spiders and a splen- 

 did monograph on the instincts and habits of wasps, 

 explains this general opinion as follows: "Under the 

 term instinct we place all complex acts that are per- 

 formed previous to experience and in a similar manner 

 by all members of the same sex and race, leaving out 

 as non-essential, at this time, the question of whether 



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