i6o ESSAYS OF A BIOLOGIST 



to the physiological : in man the physiological side, 

 though of course still basic and necessary, is more — 

 and can be much more — subordinate to the psycho- 

 logical, and all parts of the mental life interpenetrate 

 to a much greater extent ; so that the sex-instinct 

 may become transformed by a psychological process 

 roughly analogous to the transformation of physical 

 energy, and reappear in altered guise in various other 

 activities of mind. 



If we look at the matter broadly, we see that man 

 is in a period of evolutionary transition as regards sex. 

 We found previously that the greatest change connected 

 with sex which has been made in the evolution of 

 higher animals was the change by which there was 

 evolved a brain and mind with associated sense-organs 

 in which accurate perception of objects at a distance 

 could occur, a mechanism which really dominated the 

 working of the organism as a whole, and in which 

 memory and emotion seemed to play an important part. 

 Once this happened, the sex-instinct could be linked 

 up with general emotional reactions and connected 

 with external objects capable of inducing emotion. 



What was the result ? That in every group 

 possessing such a type of mind, epigamic characters of 

 a beautiful or striking or bizarre nature were evolved. 

 This first linking-up of sex with mind produced, 

 eventually, a large proportion of the beauty of the 

 organic world. It coloured and adorned not only 

 many a bird, but even newts and fish and spiders ; 



