CHAPTER XVII 



ANATOMICAL AND PSYCHIC LOCALISATION 



i. It follows from the facts of the preceding chap- 

 ter that the cerebral hemispheres are a necessary 

 organ for the phenomena of associative memory. 

 We are not quite justified in saying that they are the 

 specific organ for this function. It may be possible, 

 although not probable, that other parts of the brain 

 are also required for this purpose. It is certain that 

 the spinal cord is not needed for this function, for 

 animals whose spinal cord is severed, or from whom 

 the greater part of it has been removed, show no de- 

 ficiency in the process of associative memory. 



The cerebral hemispheres form an appendage of 

 the segmental central nervous system. They are con- 

 nected with at least some of the segmental ganglia by 

 special nerve-fibres. As these different bundles of 

 fibres enter the cortex at different places, it is obvious 

 that if we stimulate the various spots of the surface of 

 the cortex with electric currents of the smallest in- 

 tensity necessary to produce a reaction, we must 

 notice different effects. If, for instance, a current of 

 minimal intensity be sent through the spot D (Fig. 



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