VI INSTINCT AND EXPERIENCE 229 



a certain decrree, i.e. can accustom themselves to the absence 

 of enemies." 



These sentences would agree perfectly with my own views, 

 so far as they admit that acquired characters are taken up by 

 the germ-plasm ; but the words " such as must gradually take 

 place in consequence of general crossing " bring into promi- 

 nence the complete contradiction between our respective 

 doctrines — by which I do not mean to say that I do not also 

 allow some importance to pammixis in the degeneration of 

 mental characters. However, in order to estimate the degree 

 of inherited fear, e.g. in pheasants in presence of man, we 

 must rear them ourselves, and not leave them to be reared by 

 the hens ; chickens reared by the mother-hen are shy from the 

 first, those reared by man are tame directly after hatching 

 (cf. the following). 



According to my ideas, the evolution of instinct is as much 

 due to the impress of experience as the taming of the indi- 

 vidual animal ; the loss of fear in the latter in consequence of 

 experience gives the foundation for the development of in- 

 stinct — when it is inherited we call it instinct. And the 

 same holds true for the degeneration of instinct. I am unable 

 in this case any more than in morphological relations to 

 separate completely the individual and its descendants. 



To Weismann's explanation of the degeneration of the 

 food-seeking instinct, which he also discusses, I feel obliged 

 to make not only the same objections as I have made to his 

 explanation of the loss of the instinct of flight, but others in 

 addition. 



Weismann attempts to trace also to the cessation of natural 

 selection, to pammixis, the fact that various animals have 

 forgotten how to seek food, even in some cases how to feed ; 

 young birds (nestlings) are fed passively, and similarly certain 

 species of ants, and certain individuals in ant communities. 

 The red ant (Polyergus rufescens), as is well known, steals the 



