ORGANIC ADAPTATION 347 



simple factors of behavior, and leave it more or less free for the 

 higher intellectual processes. The cerebrum, regarded as the organ 

 of the mind, is superimposed upon the system of automatic, 

 machine-like responses of the reflex centers. It is the executive 

 that reacts to the state of affairs as a whole and coordinates or 

 alters responses when the routine responses are inadequate. The 

 progress of modifiability toward conscious choice-responses to ex- 

 ternal conditions constitutes a gradual and ill-defined transition 

 from instincts to associative memory, or newly conditioned 

 responses, to learning and the highest intellectual processes. 

 (Fig. 143.) 



Although it is necessary to emphasize that mind and intelligence, 

 in the biological sense, are expressions for that integration of 

 nervous states and actions which makes possible a nicety of adapta- 

 tion of behavior to environmental conditions that otherwise would 

 be impossible — that it is our chief means of adaptation ; it is a 

 serious mistake to minimize the importance of the vast gulf be- 

 tween Man's nature and that of the most highly developed lower 

 animals. In no respect are these differences more marked than in 

 the various forms of learning that collectively form the means 

 of education. While associative memory, or conditioning, will 

 account for the various non-instinctive actions of Man's animal 

 associates, human racial history and the individual's experience 

 contain much that baffles explanation in such terms. Indeed, in 

 the highest reaches of conscious life we appreciate that it is able 

 to form strange conceptions; that it has not only memory of the 

 past, but also anticipation of the future. We can brood and medi- 

 tate and understand in part. We are guided by the past, present, 

 and future in making adaptations. "The largest fact in the story 

 of evolution is the growing dominance of the mental aspect of 

 life." 



Thus it is clear that, with all the variations in structure and 

 function, organisms all possess irritability in common: they all 

 exhibit adaptive responses which enable them to exist in spite of 

 surrounding changes. "Adaptability appears to be the touchstone 

 with which nature has tested each kind of organism evolved ; it has 

 been the yard-stick with which she has measured each animal type ; 

 it has been the counterweight against which she had balanced 

 each of her productions . . .the general course of evolution has 



