ADAPTATION 193 



understood. It seems to me that this important logical 

 point has not always received the attention it deserved. 



The Regulation of Heat Production. 1 Having finished 

 our introductory remarks we now turn to the proper 

 study of special physiological functioning with regard to 

 its adaptive side, and begin with the most simple cases. 



The so-called " regulation of heat " in warm-blooded 

 vertebrates is an instance of a special function which can 

 be said to be regulatory in itself. There exists a normal 

 blood heat for each species, which is maintained no matter 

 whether the temperature of the medium rise or fall. It 

 might seem at first as if in this case there were a little 

 more of an adaptive regulation than only its well-known 

 primary type ; no reversion, one might say, of the direction 

 of one and the same process occurs in the regulation of heat 

 production, but one kind of process is called into action 

 if it is necessary to raise the temperature, and another 

 whenever it is necessary to lower it. Even in the dilatation 

 and constriction of capillary vessels there are different 

 nerves serving for each operation respectively, and far more 

 important are the increasing of transpiration for cooling, the 

 increasing of combustion for heating two radically different 

 processes. But, nevertheless, there is a certain unity in 

 these processes, in so far as a specific locality of the brain 

 has been proved to be the " centre " of them all ; it is to 

 this centre of course that the analysis of heat production 

 considered as a kind of regulation or adaptation must be 

 directed. Such an ultimate analysis, it seems to me, would 

 have to classify heat regulation under the primary type of 



* 



1 Rubner, Die Gesetze des Energieverbrauches bei der Erndhrung, Leipzig 

 u. Wien, 1902. 



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