Instinctive Behaviour of Birds 123 



overhanging bank. This was the first time the 

 bird had dived. Mr. Lloyd Morgan observes 

 that he had repeatedly endeavoured to elicit 

 this characteristic piece of behaviour, but had 

 failed. But now the blundering puppy suc- 

 ceeded in causing the small bird to execute a 

 series of complex movements which, on their 

 first occurrence, were independent of prior ex- 

 perience, and were directed towards the well- 

 being of the individual. He adds : " Such 

 behaviour is, I conceive, a more or less com- 

 plex organic or biological response to a more 

 or less complex group of stimuli of external 

 and internal origin, and it is, as such, wholly 

 dependent on how the organism, and especially 

 the nervous system and brain centres, have been 

 built through heredity under that mode of 

 racial preparation which we call biological 

 evolution." 



From the basal ganglia of a bird's brain 

 numerous nerve fibres pass to the superficial 

 layer of cells forming the pallium of its hemi- 

 spheres ; the structures entering into the forma- 

 tion of this layer are more distinctly differen- 

 tiated and of a higher type than those of the 



