THE ORGANIC TENDENCY 183 



through long periods of time. Only nervous proc- 

 esses continue to present a somewhat mystical 

 aspect. Mental activity is only beginning to 

 yield up its simpler secrets. Until these things 

 are on at least as firm a scientific basis as 

 other aspects of physiology it is not strange that 

 nervous phenomena seem less amenable to a 

 physico-chemical explanation than the better 

 known physiological processes, but scientifically 

 such an explanation seems inevitable, if remote. 



"This means, of course, that thinking is mech- 

 anistically determined, the same as flying and 

 walking; and also that thinking is a true cause of 

 subsequent events — not an epiphenomenon. We 

 do not know how the brain thinks, nor as much 

 as we would like about how a muscle contracts ; but 

 this does not forbid accepting the evidence that 

 these organs do perform these functions." ^ 



Nevertheless mind, especially as it is developed 

 in the human species, is sufiiciently unique to com- 

 mand our attention as a possibly novel factor in 

 evolution. To what extent may it have influenced 

 the development of animals^ as it has gradually 

 advanced in importance to the individual.^ To 

 what organic property does it owe its origin .^^ Is it 

 universal in all organisms in one or another stage 

 of development .f^ And is it effective even in its 



2 Herrick, C. J., Brains of Rats and Men, p. 17, 1926. Reprinted by per- 

 mission of the University of Chicago Press. 



