80 



THE EYE IN EVOLUTION 



Figs. 51 and 52. — The Reactions of the Digger Wasp. 



Fig. 51. — The wasp, Philanthus triangulum, on leaving the nest in the centre 

 of the ring of pine cones, makes a locaUty-study lasting 6 seconds and 

 then leaves. 



Nest ' 



■^^ ^ k. 



Fig. 52. — The ring of pine cones is then displaced from the nest and on her 

 return the wasp alights in the centre of the ring and will only find the 

 nest after the original situation has been restored (Tinbergen, Study of 

 Instinct; Clarendon Press). 



begun to elucidate the more complex aspects of animal psychology in 

 which the basic instinctive reactions are modified by experience of 

 the past. 



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von Buttel-Reepen. Naturwiss. Wschr., 



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11, 107 (1930) ; 14, 629 (1931). 



