108 THE BRAIN OF THE TIGER SALAMANDER 



dimension as "any manifold which can be ordered," as Reiser ('46, 

 p. 89) does in an interesting discussion of this problem. 



The theories of mind-body relationships are mentioned here be- 

 cause I regard mentation as a vital process as truly as are muscular 

 contraction and glandular secretion. The laws of operation of these 

 three processes are different, their products are different, and the 

 apparatus employed is different. All these operations have locus in 

 place and time. The organs which perform them have been slowly 

 differentiated and matured during embryonic and phyletic history. 

 We have reason to believe that mind is not an exclusive prerogative 

 of mankind. Mental capacity has developed parallel with the growth 

 of its organs. The genetic and phylogenetic approach to the mind- 

 body problem has already yielded significant data; and, as this study 

 is carried backward toward earlier stages (embryonic and phyletic), 

 the unresolved problems of human psychophysics do not disappear. 

 Something akin to the mental as we experience it may be a com- 

 mon property of all living things and even of the cosmos as a whole, 

 as some suppose. Or it may be that, just as life emerged on our planet 

 from the nonliving in some as yet undiscovered way, so mind ap- 

 peared as an emergent at some unknown stage of organic evolution. 

 If so, the naturalist must assume that the emergence in both cases 

 occurred in lawfully ordered ways within the frame of the natural. 

 In the present state of knowledge an open-minded skepticism on this 

 question is the only safe attitude. 



More intensive study of the properties of the nervous tissues seems 

 to be the most promising approach to these unsolved problems. In 

 the past, escape from mystery has too often been sought through 

 verbalisms and mysticism. Rigid adherence to scientific method — 

 accepting as evidence not wishful thinking but verifiable experi- 

 ence — will avoid this pitfall. Obviously, conventional methods of 

 inquiry must be pushed to the limit of their availability, and in the 

 meantime new formulations of problems must be sought with all the 

 resourcefulness that scientific imagination can command, not neg- 

 lecting the possibility that some of these formulations may lie outside 

 the frame of current Newtonian and quantum mechanics. 



