CHAPTER VIII 



SOME "cold-blooded" LOVERS * 



The Courtship of the Crocodile — Amorous Lizards — Horned Chamae- 

 leons — A flagellating Terrapin — The Frog that would a-wooing 

 go — Semo musical Frogs — Some marvellous instincts in Newts. 



The measure of the vitality of animals may be estimated 

 by their response to stimuli ; and their behaviour increases 

 in variety and complexity as the nervous system develops. 

 Our interpretation of that behaviour commonly leaves 

 out of account the character of this responsiveness : we 

 are apt to see proof of intelligence in acts which should 

 be read as instinctive. And instinct is to be regarded as 

 a co-ordinated response to stimulus, independent of prior 

 experience. 



The complexity of this response stands in very close 

 relation to the structural complexity of the organism 

 in which it occurs, and this because an ever-increasing 

 number of mechanisms and actions must be set in motion 

 to carry out the fulfilment of any given stimulus, as this 

 is traced from the lower to the higher groups of animals : 

 till at last we have to distinguish between movements 

 that are merely reflexes, and those which are " instinctive." 

 The latter must be fulfilled by the former — the reflex 



i6i II 



