INSTINCT. 391 



object O, on which he has an instinctive impulse to react in 

 the manner A, would directly provoke him to that reaction. 

 But O has meantime become for him a sign of the nearness 

 of P, on which he has an equally strong impulse to react in 

 the manner B, quite unlike A. So that when he meets O 

 the immediate impulse A and the remote impulse B strug- 

 gle in his breast for the mastery. The fatality and unifor- 

 mity said to be characteristic of instinctive actions will be 

 so little manifest that one might be tempted to deny to him 

 altogether the possession of any instinct about the object 

 O. Yet how false this judgment would be ! The instinct 

 about O is there ; only by the complication of the associa- 

 tive machinery it has come into conflict with another in- 

 stinct about P. 



Here we immediately reap the good fruits of our simple 

 physiological conception of what an instinct is. If it be a 

 mere excito-motor impulse, due to the pre-existence of a 

 certain ' reflex arc ' in the nerve-centres of the creature, of 

 course it must follow the law of all such reflex arcs. One 

 liability of such arcs is to have their activity 'inhibited,' by 

 other processes going on at the same time. It makes no 

 difference whether the arc be organized at birth, or ripen 

 spontaneousl}' later, or be due to acquired habit, it must 

 take its chances with all the other arcs, and sometimes 

 succeed, and sometimes fail, in drafting off the currents 

 through itself. The mystical view of an instinct would 

 make it invariable. The physiological view would require 

 it to show occasional irregularities in any animal in whom 

 the number of separate instincts, and the possible entrance 

 of the same stimiilus into several of them, were great. And 

 such irregularities are what every superior animal's in- 

 stincts do show in abundance.* 



* In the instiuctsof mammals, and even of lower creatures, the uniform- 

 ity and infallibility which, a generation ago, were considered as essential 

 characters do not exist. The minuter study of recent years has found con- 

 tinuity, transition, variation, and mistake, wherever it has looked for them, 

 and decided that what is called an instinct is usually only a tendency to 

 act in a way of which the average is pretty constant, but which need not 

 be mathematically 'true.' Cf. on this point Darwin's Origin of Species: 

 Romanes's ]\Iental Evol., chaps, xi to xvi inch, and Appendix; W. L. 

 Lindsay's Mind in Lower Animals, vol. i. 133-141 ; ii. chaps, v, xx ; 



