CHAPTER XXIV.* 

 INSTINCT. 



Instinct is usually defined as the faculty of acting in such a 

 way as to produxie certain ends, ivithout foresight of the ends, 

 and ivithout previous education in the performance. That 

 instincts, as thus defined, exist on an enormous scale in the 

 animal kingdom needs no proof. They are the functional 

 correlatives of structure. With the presence of a certain 

 organ goes, one may say, almost always a native aj)titude 

 for its use. 



" Has the bird a gland for the secretion of oil ? She knows instinc- 

 tively how to press the oil from the gland, and apply it to the feather. 

 Has the rattlesnake the grooved tooth and gland of poison ? He knows 

 without instruction how to make both structure and function most ef- 

 fective against his enemies. Has the silk- worm the function of secret- 

 ing the fluid silk ? At the proper time she winds the cocoon such as she 

 has never seen, as thousands before have done ; and thus without in- 

 struction, pattern, or experience, forms a safe abode for herself in the 

 period of transformation. Has the hawk talons ? She knows by in- 

 stinct how to wield them effectively against the helpless quarry, "f 



A very common way of talking about these admirably 

 definite tendencies to act is by naming abstractly the pur- 

 pose they subserve, such as self-preservation, or defence, or 

 care for eggs and young — and saying the animal has an in- 

 stinctive fear of death or love of life, or that she has an in- 

 stinct of self-preservation, or an instinct of maternity and 

 the like. But this represents the animal as obeying ab- 

 stractions which not once in a million cases is it possible it 

 can have framed. The strict physiological way of interpret- 



* This chapter has already appeared (almost exactly as now printed) in 

 the form of magazine articles in Scribner's Magazine and in the Popular 

 Science Monthly for 1887. 



t P. A. Chadbourne : Instinct, p. 28 (New York, 1872). 



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