GENERAL BIOLOGY. 41 



THE LAW OF HABIT. 



Every one must have observed in himself and others the 

 tendency to fall into set ways of doing certain things, in which 

 will and clear purpose do not come prominently into view. 

 Further observation shows that the lower animals exhibit this 

 tendency, so that, for example, the habits of the horse or the dog 

 may be an amusing reflection of those of the master. Trees are 

 seen to bend permanently in the direction toward which the 

 prevailing winds blow. 



The violin that has experienced the vibrations, aroused by 

 some master's hand acquires a potential musical capability not 

 possessed by an instrument equally good originally, but the 

 molecular movements of which never received such an educa- 

 tion. 



It appears, then, that underlying what we call habit, there is 

 some broad law not confined to living things ; indeed, the law 

 of habit appears to be closely related to the law of rhythm we 

 have already noticed. Certain it is that it is inseparable from 

 all biological phenomena, though most manifest in those organ- 

 isms provided with a nervous system, and in that system itself. 

 What we usually call habit, however expressed, has its physical 

 correlation in the nervous system. We may refer to it in this 

 connection later: but the subject has relations so numerous 

 and fundamental that it seems eminently proper to introduce 

 it at this early stage, forming as it does one of those corner- 

 stones of the biological building on which the superstructure 

 must rest. 



When we seek to come to a final explanation of habit in this 

 case, as in most others, in which the fundamental is involved, 

 we are soon brought against a wall over which we are unable 

 to cUmb, and through which no light comes to our intellects. 



We must simply believe, as the result of observation, that it 

 is a law of matter, in all the forms manifested to us, to assume 

 accustomed modes of behavior, perhaps we may say molecular 

 movement, in obedience to inherent tendencies. But, to recog- 

 nize this, throws a flood of light on what would be inexplicable, 

 even in a minor degree. We can not explain gravitation in it- 

 self ; but, assuming its universality, replaces chaos by order in 

 our speculations on matter. 



Turning to living matter, we look for the origin of habit in 

 the apparently universal principle that primary molecular 



