200 INSTINCT. [Chap. VIII 



Several other points of resemblance between instincts and habits 

 could be pointed out. As in repeating a well-known song, so in 

 instincts, one action follows another by a sort of rhythm ; if a person 

 be interrupted in a song, or in repeating anything by rote, he is 

 generally forced to go back to recover the habitual train of thought, 

 so P. Huber found it was with a caterpillar, which makes a very com- 

 plicated hammock ; for if he took a caterpillar which had completed 

 its hammock up to, say, the sixth stage of construction, and put it 

 into a hammock completed up only to the third stage, the caterpillar 

 simply re-performed the fourth, fifth, and sixth stages of construction. 

 If, however, a caterpillar were taken out of a hammock made up, 

 for instance, to the third stage, and were put into one finished up to 

 the sixth stage, so that much of its work was already done for it, 

 far from deriving any benefit from this, it was much embarrassed, 

 and in order to complete its hammock, seemed forced to start from 

 the third stage, where it had left off, and thus tried to complete the 

 already finished work. 



If we suppose any habitual action to become inherited — and it 

 can be shown that this does sometimes happen — then the resem- 

 blance between what originally was a habit and an instinct becomes 

 so close as not to be distinguished. If Mozart, instead of playing 

 the pianoforte at three years old with wonderfully little practice, 

 had played a tune with no practice at all, he might truly be said 

 to have done so instinctively. But it would be a serious error to 

 suppose that the greater number of instincts have been acquired by 

 habit in one generation, and then transmitted by inheritance to 

 succeeding generations. It can be clearly shown that the most 

 wonderful instincts with which Ave are acquainted, namely, those 

 of the hive-bee and of many ants, could not possibly have been 

 acquired by habit. 



It will be universally admitted that instincts are as important as 

 corporeal structures for the welfare of each species, under its present 

 conditions of life. Under changed conditions of life, it is at least 

 possible that slight modifications of instinct might be profitable to 

 a species ; and if it can be shown that instincts do vary ever so 

 little, then I can see no difficulty in natural selection preserving 

 and continually accumulating variations of instinct to any extent 

 that was profitable. It is thus, as I believe, that all the most 

 complex and wonderful instincts have originated. As modifications 

 of corporeal structure arise from, and are increased by, use or habit, 

 ■and are diminished or lost by disuse, so I do not doubt it has been 

 with instincts. But I believe that the effects of habit are in many 

 cases of subordinate importance to the effects of the natural selection 



