70 THE PLAY OF ANIMALS. 



chase, who are perfectly conscious of the object of their 

 actions and yet are in great part impelled by instinctive 

 impulses. If such half-instinctive phenomena are in- 

 cluded in the category, then man has as many instincts 

 as any animal, if not more. By this elucidation we 

 reach the truth that lies concealed in the theory men- 

 tioned above — namely, that the lower the animal stands 

 the purer are its instincts; the higher its place the more 

 will the hereditary tracts be weakened, altered, or sup- 

 planted by acquired tracts. " The more various and 

 ready the inherited mechanical impulses of a class of 

 animals," say the Miillers, " the less do we find of in- 

 dependent mental capacity." * And Flourens remarks, 

 " Intelligence does not enter into instinct, but it influ- 

 ences it, protects it, and alters circumstances to suit it, 

 and this agreement between instinct and intelligence is 

 well worth attention." f 



I am now firmly convinced that this relation is itself 

 eminently useful, and that it is due to negative as well as 

 positive selection. Hartmann has already pointed out 

 that Nature substitutes instinct where the means are not 

 at hand for conscious action or acquisition. J The higher 

 and more complicated the scale of activity which the 

 struggle for existence requires of a species the more will 

 selection favour development of the brain and of the 

 mental capacities. The more these increase by means 

 of positive selection the less will its aid be needed in the 

 sphere of instinct. The result will be that fewer indi- 

 viduals will have completely developed hereditary tracts 



* A. and K. Miiller, Wohnungen, Leben und Eigenthumlich- 

 keiten in der hQheren Thierwelt, p. 217. 



f P. Flourens, Psychologie comparee, second edition, 1864, p. 10. 

 See also J. Sully, The Human Mind, 1892, i, p. 137. 



X Hartmann, Philos. d. Unbewussten, i, p. 185. 



