APPLETONS' 



POPULAR SCIENCE 

 MONTHLY. 



FEBRUARY, 1898. 



THE EVOLUTION OF THE MIND. 



By DAVID STAER JORDAN, 



PRESIDENT OF I/ELAND STANFORD JUNIOR UNIVERSITY. 



THE mind, in the sense in which I shall here nse the word, is the 

 collective function of the sensorium or brain of man and ani- 

 mals. It is the sum total of all psychic changes, actions, and reac- 

 tions. Under the head of psychic functions are included all opera- 

 tions of the nervous system, as well as operations of like nature which 

 take place in creatures without specialized nerve fibers or nerve cells. 



As thus defined, mental operations are not necessarily or exclu- 

 sively conscious. With the lower animals nearly all of them are 

 automatic and unconscious. Even with man, most of them must be 

 so. But between the automatic and the conscious actions no sharp 

 line of division exists. All functions of the nervous system are 

 alike in nature, and from the present point of view may be considered 

 together. Consciousness is not an entity, but a condition. It 

 stands related to mind much as flame is related to fire. 



It is a recognized law in biology that " function precedes struc- 

 ture." To define this law more exactly, we should say that function 

 precedes the differentiation of the organ on which it depends. 

 There is a certain work to be done, and a certain body of cells are set 

 apart sooner or later to do it. Just as plowing was done in some 

 fashion before the invention of the plow, so in some manner respira- 

 tion was accomplished before the development of gills and lungs. 

 Something of mental action came before there was ever an organized 

 brain. 



In the animals of one cell, or protozoa, breathing and digestion 

 are each performed by the whole body. In the division of labor or 



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