INTRODUCTION 



through pointing out the need of supplement- 

 ing natural selection by other factors. " Direct 

 adaptation " appears as necessary to an expla- 

 nation of the evolution of sense-organs, such as 

 the eye and the ear, and to the meeting of other 

 difficulties in the way of the hypothesis of Dar- 

 win. The arguments are in the sense of Spen- 

 cer's general discussion in Part III. of the "Bi- 

 ology." Fiske thus leads over to a statement, 

 in chapter xiii., of the Spencerian definition of 

 " Life as Adjustment.'* This now so famous 

 definition is developed at length by Spencer in 

 Part I. of the " Biology," chapters iv., v., and 

 vi. Fiske's summary is brief, and is intended 

 chiefly to prepare the reader for the discussion 

 of the psychological theories which immediately 

 follow. 



20. Chapter xiv., on " Life and Mind," is 

 an exposition of the Spencerian definition of 

 the nature of mental processes. Except to show 

 his usual care in insisting upon the contrast 

 between mental and physical phenomena, and 

 in warding off any tendency on the reader's 

 part to interpret Spencer's doctrine as at all 

 verging towards materialism, Fiske's exposition 

 here involves no features upon which our at- 

 tention need at present rest. The polemic 

 against Comte continues. But chapter xv., on 

 " The Composition of Mind," undertakes to 

 Ixv 



