INSTINCT AND INTELLIGENCE 



zation, but not to be taken for an absolutely true ex- 

 pression of all the facts. This kind of perplexity is well 

 understood and allowed for in all morphological work, 

 but it has never been fully realized in the study of habits. 

 The explanation is not far to seek. The habits of but 

 few animals have been studied in sufficient detail to 

 bring out the evidence that there is as much variation 

 on the psychological as on the morphological side, 

 although this field seems fresh and inviting when com- 

 pared with the researches of the laboratory. 



The necessity of interpreting the actions of animals 

 in terms of our own consciousness must be always with 

 us. To interpret them at all we must consider what our 

 own mental states would be under similar circumstances, 

 our safeguard being to keep always before us the pro- 

 gressive weakening of the evidence as we apply it to 

 animals whose structure is less and less like our own. 



We arrange the activities of the wasps that we have 

 studied into two groups, Instincts, and Acts of Intelli- 

 gence, it being understood that these classes pass by 

 insensible stages into each other, and that acts that 

 are purely instinctive when performed for the first time 

 are probably in some degree modified by individual 

 experience. In this classification the question of origin 

 is not considered. The facts are grouped under the 

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