156 Journal of Comparative Neurology. 



belief that the whole of the cortical complex is adapted to re- 

 act as a unit, though not as an invariable unit. The great ex- 

 tent of the system of associational tracts and the facility with 

 which new channels of overflow are set up or marked out is 

 additional evidence in favor of an equilibrium theory of con- 

 sciousness such as has been advocated by the writer for several 

 years. In this view, the conditions of consciousness consist in 

 the proper equilibration of stimuli to produce a reflection of 

 the stimuli upon the complex of which they form a part. The 

 mechanism of this condition is found in the cortical centres, 

 which are in continual action in such a way that a vortex of 

 activity is in continual flux — each element contributing to the 

 balance of the whole. To this complex external stimuli are 

 continually being admitted, whether as separately unobserved 

 elements from the general-sensation apparatus of the common 

 sensorium (giving rise simply to the implicate concept of per- 

 sonal existence in space), or more specific stimuli through the 

 avenues of the special sense organs. Every sense-content with 

 its escort of reflexly-produced associated elements causes a 

 more or less profound disturbance of the psychical equilibrium 

 and the nature of this disturbance depends hot alone on the in- 

 tensity and state of concentration, but very largely upon the 

 kind of equilibrium already existing. In no case is it possible 

 for consciousness to be double or for more than one conscious 

 act to occur at a time. 



It is believed that by the employment of the equilibrium 

 theory we may reach as clear an idea of the conditions and lim- 

 itations of consciousness as the nature of the case could war- 

 rant us in expecting. The character of the conscious act (and 

 the elements of consciousness are always acts) will of course 

 depend upon the extent to which the several factors in the asso- 

 ciational system participate in the equilibration. Each disturb- 

 ance of equilibrium spreads from the point of impact in such a 

 way that progressively more of the possible reflex currents en- 

 ter the complex, thus producing the extension from mere sen- 

 sation to the higher processes of apperceptive association. A 

 conscious act is always a fluctuation of equilibrium, so that all 



