x THE FORE-BRAIN 631 



with the periphery by exogenous fibres. Their functional synergy 

 depended on the central confluence of these sensory spheres, which 

 rendered the cerebrum the single organ of intelligence. Munk's 

 general hypothesis of the psycho-physiological functions of the 

 brain is based upon this schema of Meynert and Wernicke. 



According to our own theory, which is based on experimental 

 work on dogs, the several sensory centres overlap in a common 

 area to which we gave the name of " centre of centres." Flechsig, 

 too, admits that there is no absolute line of demarcation between 

 his cortical projection fields, which include the sensory and motor 

 areas, and the association fields. Between the one and the other 

 Flechsig sees the same relations as exist between sensibility and 

 intelligence " which, while theoretically separable, are really 

 intimately associated." NiMl est in intellectu quia prius fuerit in 

 sensibus. Without the sensory centres, the intellectual centres 

 would be ab initio incapable of producing ideas or representations ; 

 both normally act and react together, work for the same ends, and 

 aim at the same results. The material supplied by the sensations 

 is, so to speak, elaborated in the intellectual centres. The 

 functions of the one represent the receptive phase, those of the 

 other the reactive phase of the mental process. The former (to 

 adopt the classical language of Aristotle) constitute the passive 

 intellect, the latter the active intellect. 



It was the clinicians arguing from the symptoms of aphasia 

 who first postulated the existence of an ideational centre in the 

 cortex distinct from the centres for verbal images (auditory, visual, 

 articulative). The fact that there may be total loss of the use of 

 words with no apparent disturbance of intelligence is the most 

 cogent argument that the word and the idea are formed in- 

 dependently of one another, in different areas of the cerebral 

 cortex. But it was only from the studies of Flechsig that this 

 hypothetical ideational centre acquired a localisation, though still 

 indefinite and vague. It is evident that it must lie in the associa- 

 tion fields, more particularly in those contained within the parieto- 

 occipito-temporal area of Flechsig. 



The distinction between sensory -motor and psychical areas of 

 the cortex is intimately connected with an important question 

 of the general theory of Memory. Is the seat of primary precepts 

 or sensory images identical with or different from that of the 

 secondary representations or the secondary sensory images, evoked 

 by a simple effort of memory ? If the first hypothesis, which has 

 been formulated by Ribot and other psychologists, and accepted 

 unconditionally by physiologists and clinicians, be admitted it 

 follows that the sensory centres on which perception of the 

 external world depends are at the same time the seat at which the 

 memory images must be formed and stored up, but we are unable 

 to picture or to comprehend their nature. If we accept the second 



