INSTINCT AND INTELLIGENCE. 66 1 



others. And this convinces me that there is yet a higher philosophy 

 on this subject which I have not reached. 



Formation of Habits. We are all familiar with this process. A 

 movement or series of movements at first painfully difficult, and re- 

 quiring the whole thought and attention, by repetition become so easy 

 and semi-automatic that attention is no longer necessary. The most 

 remarkable examples of these, such as walking, speaking, and the 

 like, probably belong partly to the third category; the capacity for 

 these is partly inherited. Playing on a musical instrument is therefore 

 a better example. We all know the painful attention necessary at 

 first, and the ease and rapidity of the most complex movements at- 

 tained by practice. Now, by what means, anatomical or physiologi- 

 cal, do these at first difficult movements become by repetition easy ? 

 The answer in general terms seems to be this: Every volitional act is 

 attended with a change in the brain, which, however, is slight, liable 

 to be effaced by subsequent changes, and therefore evanescent. If the 

 same act, however, be repeated many times, the change becomes deep 

 2t,n^ permanent \iecoxixes ptetrijiecl in brain-structure j and this struct- 

 ure, whatever be its character or its seat, determines the appropriate 

 acts with precision. It is as if every volitional act produced a faint 

 line, liable to be erased, on the tablet of the brain ; by running over 

 the same lines many times, these are deepened into grooves and finally 

 into ruts, and motion in these becomes easy and certain because the 

 ruts guide the motion instead of the will. Thus repetition produces 

 structure and structure determines habit. 



Formation of Instincts. The structure produced by repetition 

 of voluntary acts, and which, as we have seen, determines habits, by 

 the law of inheritance is transmitted in a slight degree to the next 

 generation. I say in a slight degree only, because inheritance is from 

 the whole line of ancestry and not from the immediate parents alone. 

 The inheritance from the immediate parents is greater, it is true, than 

 from any one of the series of previous generations, but infinitely less 

 than the sum of inheritances from all previous generations. The struct- 

 ure may be regarded, therefore, as transmitted in an almost etFaced 

 condition. If the same acts are not repeated, the lines of structure 

 are soon wholly effaced by new lines running across the tablet in all 

 directions ; but if they are repeated the same lines are deepened with 

 greater ease and certainty than before ; the structure becomes still 

 more decided, the habit still more fixed. This more deeply-engraved 

 structure is again j^artially transmitted to be again strengthened in 

 the next generation the engraved plate is retouched and the lines 

 deepened. Thus with every generation the sum of inheritance be- 

 comes greater because from a greater number of preceding genera- 

 tions ; with every generation the effacement by transmission is less, 

 and the deepening by repetition is greater, until finally a highly-differ- 

 entiated structure is formed, and perfectly transmitted a structure 



