202 BRAINS OF RATS AND MEN 



energetics, in the dynamics of cerebral function. The 

 animal body, and the nervous system in particular, 

 may be regarded as a very complex mechanism for 

 the transmission and transformation of energy. The 

 sources of this energy are largely internal, reserves of 

 potential in unstable equilibrium. When this equili- 

 brium is upset, as by an external stimulus, there is an 

 immediate readjustment tending to restoration of 

 equilibrium, typically by an overt act of some sort, 

 such as entering the maze to secure food. 



If the natural innate reflex apparatus is adequate 

 to resolve the situation, the reaction is consummated 

 immediately with minimum of energy, as happens 

 when accessible food is placed before a hungry rat. In 

 a more complex situation for which no ready-made in- 

 nate apparatus is provided, such as the selection of a 

 lighted alley, the necessary nervous circuits must be 

 in some way set apart and re-integrated, that is, 

 "made-to-order," before the reaction is automatized. 

 This may be done by the method of trial-and-error, 

 as already outlined. This is biologically a much more 

 expensive process than the direct reflex response, and 

 the organic reserves are heavily drawn upon. In the 

 absence of cortex the thalamic reserves are adequate 

 for this reaction. But when cortex is present the ana- 

 tomical organization is such that the cortical reserves 

 are tapped and the cortex becomes a more or less im- 

 portant source of the energies employed in the labori- 

 ous process of automatization of the habit. 



