VARIATION OF INSTINCT IN DEFINITE LINES. 219 



CHAPTER XIV. 



Instinct (continued). 



Modes in which Intelligence determines the Variation 

 of Instinct in Definite Lines. 



"We have now seen that instincts may have what I term a 

 blended origin — or, in other words, that intelligent adjust- 

 ment by going hand in hand with natural selection, must 

 greatly assist the latter principle in the work of forming 

 instincts, inasmuch as it supplies to natural selection varia- 

 tions which are not merely fortuitous, but from the first 

 adaptive. I shall next show what I conceive to be the chief 

 modes in which intelligence thus operates, or co-operates 

 with selection, in the formation of instincts. 



Of course in general terms it is easy to see that the mode 

 in which intelligence thus co-operates is by enabling an 

 animal to perceive that, owing probably to some change in 



environment, it may best adapt itself to the existing con- 

 ditions of its life by deviating in some degree from its 

 ancestral instincts (as when the tailor-bird seeks for threads 

 of cotton instead of fibres of grass wherewith to sew its nest), 

 or by intelligent observation giving rise to adjustive actions, 

 which by repetition had to an instinct cle novo (as in the 

 case of the honey-guide, which has acquired the remarkable 

 instinct of attracting the attention of man, and leading him 

 to the nests of bees).* But with animals, as with men, 

 original ideas are not always forthcoming at the time they 

 are wanted, and therefore it is often easier to imitate than 



to invent. Thus, the first mode which I shall consider 

 whereby intelligence may change or deflect an instinct, is 

 that of imitation, for although it is true that the initial 

 stage of such deflection occurs in the "original ideas," nothing 



• See Animal Jnhlhi/encr, p. 315. 



