i895- SOME DEFINITIONS OF INSTINCT. 325 



loses the ' instinctive ' demeanour, and appears to lead a life of hesitation 

 and choice, an intellectual life ; not, however, because he has no instincts — 

 rather because he has so many that they block each other's path." This is in 

 tolerably marked contrast with the statement of Darwin's which stands 

 at the head of this section ! 



6. The Plasticity and Variability of Instinct. — " Though the 

 instincts of animals," said Douglas Spalding, 35 "appearand disappear 

 in such seasonable correspondence with their own wants and the 

 wants of their offspring as to be a standing subject of wonder, 

 they have by no means the fixed and unalterable character by which 

 some would distinguish them from the higher faculties of the human 

 race. They vary in the individuals as does their physical structure. 

 Animals can learn what they did not know by instinct, and forget the 

 instinctive knowledge which they never learned, while their instincts 

 will often accommodate themselves to considerable changes in the 

 order of external events." It will be noticed that there are here two 

 groups of facts: (1) variations, analogous to variations in physical 

 structure ; and (2) accommodations to changes in the external order of 

 events. Professor James 36 says, "the mystical view of an instinct 

 would make it invariable " ; and he formulates two principles of non- 

 uniformity of instincts, (1) that of the inhibition of instinct by habits ; 

 and (2) that of the transitoriness of instincts. The variation analogous 

 to that of physical structure is not here explicitly recognised. 

 Romanes, who defines 3 ? instinct as a generic term comprising " all 

 those faculties of mind which are concerned with conscious and 

 adaptive action, antecedent to individual experience . . . and 

 similarly performed under similar and frequently recurring circum- 

 stances by all the individuals of the same species," appears to lay 

 stress on their invariability ; but his subsequent treatment 38 shows 

 that he fully recognised the connate variability of instinct. Under the 

 head of "plasticity" he also 3 9 insisted on "the modifiability of instinct 

 under the influence of intelligence." He quotes, with approval, 

 Huber's exclamation : " How ductile is the instinct of bees, and how 

 readily it adapts itself to the place, the circumstances, and the needs 

 of the community." There seems, however, some want of logical 

 consistency in first defining instinct as connate and antecedent to 

 individual experience, and then implying that, as modified under the 

 influence of experience, it still remains instinct. For example, 

 Romanes says -* : " There is evidence to show that the knowledge 

 which animals display of poisonous herbs is of the nature of a mixed 

 instinct, due to intelligent observation, imitation, natural selection and 



85 E.g., Douglas Spalding. Instinct and Acquisition. Nature, vol. xii., p. 507. 



36 " Principles of Psychology," vol. ii., pp. 39 I_ 4- 



" " Mental Evolution in Animals," p. 159. 



ss Op. cit., p. 190. Cf. Darwin, in the same work, pp. 372 and 383. 



39 Op. cit., p. 203. 



40 Op. cit., p. 227. 



