350 ZOOLOGICAL PHILOSOPHY 



that the fluid cuts out a route which becomes specially easy for it to 

 traverse, and that it acquires a readiness to follow this route in pre- 

 ference to others. 



How great is the light shed by this simple and fertile principle on 

 the power of habit — a power from which even man can only escape 

 with great difficulty by the help of his highly developed intellect ! 



Who can now deny that the power of habits over actions is inversely 

 proportional to the intelhgence of the individual, and to the develop- 

 ment of his faculty of thinking, reflecting, combining his ideas, and 

 varying his actions ? 



Animals, which are only sensitive, and have not yet acquired the 

 organ in which are produced comparisons between ideas, as also 

 thoughts, reasonings and the various acts constituting intelligence, 

 have nothing but perceptions (often very confused), do not reason, 

 and can make httle variation in their actions. They are therefore 

 permanently subject to the power of habit. 



Thus insects, which have the least developed nervous system of 

 any animals that possess feeling, experience perceptions of the objects 

 which affect them, and seem to possess a memory gained through a 

 repetition of these perceptions. They can, however, neither vary 

 their actions nor alter their habits, since they possess no organ to 

 give them this power. 



Of Instinct in Animals. 



By instinct is meant the fixed tendencies displayed by animals in 

 their actions ; and many people have held that these tendencies are 

 the produce of a reasoned choice, and therefore the fruit of experience. 

 Others, as Cabanis said, prefer to think, in common with observers 

 of all ages, that many of these tendencies cannot be referred to any 

 sort of reasoning, and that, although taking their origin in physical 

 sensibility, they are usually formed without any share of the individual's 

 will, beyond that of improving their execution. 



If attention had been paid to the fact that all animals which can 

 feel have an inner feeling capable of being stirred by their needs, and 

 that the resulting movements of their nervous fluid are always con- 

 trolled by this inner feehng and by habit, it would then have been 

 apparent that in all such animals that are devoid of intelhgence, the 

 tendencies of action can never be the product of a reasoned choice or 

 judgment or experience turned to account, or will, but that they are 

 subject to needs, excited by certain sensations, which then awake 

 irresistible propensities. Even in animals which possess some degree 

 of intelhgence, the actions are still commonly controlled by the inner 

 feehng and by habit. 



