130 Tin; \KKvnis SISIKM \\\> ITS CONSKKYATIOX 



The performances <>f the cerebral cortex have been 

 likened to tho-e of an orchestra. The comparison would 

 have Keen acceptable either to an old-fashioned phrenol- 

 ogist or to a believer in the diffuse distribution of brain 

 activity. A series of solos by different instruments 

 would symbolize the phrenologic conception; a harmoni- 

 ous production of music by many or all the players would 

 represent the other interpretation. Local injury, accord- 

 ing to the first view, would be the silencing of a solo 

 instrument and would cause intervals of stillness in the 

 symphony. If the second view were found to be correct, 

 the local damage would not result in absolute interruption 

 of the music, but only in lessening its volume and rich- 

 ness. 



It is difficult to say exactly what is meant by "cerebral 

 localisation." In all probability, the term does not mean 

 the same to different ]>eople who use it. It would seem 

 that to some it has meant that definite regions of tin- 

 cortex are in receipt of certain impressions, and can, at a 

 later time, give rise to impulses determined by these 

 stored impressions. Descartes must have had some such 

 an idea as this when lie likened the retention of memories 

 to the imprint of a seal upon wax. Quite another view 

 is possible, and, indeed, it is the preferred one at the 

 pre-ent time. This is the conception that a given func- 

 tion appears to be connected with a given area simply 

 because so many of the paths necessary to that function 

 lie within the patch of cortex in question. 



To appreciate the modern interpretation of the working 

 of the cerebrum it is necessary to keep always before one 

 the reflex principle. \\'e readily apply this principle to 

 the spinal cord. Impulses How in and, in consequence, 

 others are sent out. It is not dillicult to extend this to 

 the medulla, ! he midbrain. and the cerebellum; the chief 

 difference between the responses from these parts and 

 from the cord lies in the greater length of the pathways 

 pursued by the impulses, the greater number of synapse- 

 crossed, and the increased capacity for variation. When 



