IRENAUS EIBL-EIBESFELDT 59 



several patterns are best employed to perform an integrated function is 

 indubitably learned. But no ethologist had ever doubted — as critics of 

 ethology often imply — that learning processes are of the greatest impor- 

 tance in behaviour, Lorenz (1937) has often emphasized that learned and 

 innate elements of behaviour are closely interwoven. His ravens for 

 example had innate nest-building movements, but had to learn which 

 material to use for nest building. Eibl-Eibesfeldt (1956b) has recently 

 shown that red squirrels develop individually different techniques of nut 

 opening on the basis of a few innate patterns, such as gnawing and a 

 certain splitting movement. 



In retrieving, learning plays a lesser role than in nest building. The 

 inhibition of biting the nestling seemed even stronger in inexperienced 

 rats. It would seem that the rat has to learn that a baby is not so vulnerable 

 after all. 



(h) The killing tecluiiqtic of the pok'cat (Putorius putorius L.). The follow- 

 ing deals with the technique of prey killing of inexperienced and exper- 

 ienced polecats. Kuo (1930) has studied the behaviour of cats raised under 

 different conditions towards albino rats, grey Norway rats and nnce. 

 Twenty cats were raised in isolation from weaning, twenty-one cats 

 remained with their mother and were allowed to observe how she killed 

 prey, and eighteen cats isolated from other cats were given a rat as com- 

 panion from an early age on. Of those raised in isolation, nine killed prey 

 (= 25 per cent); of the second group eighteen killed prey (85 per cent); 

 but of those raised with rats, only three killed prey and then only of a 

 type to which they were not accustomed. Towards their rat-companions 

 the latter individuals showed peaceful and positive reactions. They licked 

 and defended them and searched for them persistently if they were taken 

 away. Kuo thus clearly showed that experience influences the behaviour 

 of the cat towards prey, even though the difference in the percentage of 

 killing in the first two groups might be explained as a result of a different 

 state of health due to deprivation. Kuo expresses the opinion that the 

 concept of instinct has been proved useless by his experiments. The bodily 

 structures alone explain why a cat behaves like a cat and not like an ape : 

 one does not need to have recourse to instincts, based on special structures 

 of the central nervous system. What the animal actually does, within the 

 potentiality given by its body, is learned during ontogeny. 'The behaviour 

 of an organism is a passive affair. How an animal or a man will behave in a 

 given situation depends on how it has been brought up and how it is 

 stimulated' (Kuo, p. 37). 



It seems, nevertheless, that Kuo did not realize where the problem 



