LOCALIZATION OF THE CEREBRAL FUNCTIONS. 647 



From the other facts mentioned viz., the recovery of function 

 after injury, or the complete absence of functional lesion we 

 must conclude that these local areas are by no means the only 

 agents which can carry on the business of receiving for the mind 

 impulses from the periphery, and sending out voluntary impulses 

 to the muscles ; but that rather there are many groups of nerve 

 cells, in relation with the nearest sub-agents the basal ganglia 

 which can take on the duty of the injured cells, and act as cortical 

 centres, receiving sensory, and discharging motor impulses. In 

 respect of this capability of one part of the cerebral cortex to 

 carry on the duties ordinarily allocated to another, we have a 

 complete analogy in the gray part of the spinal cord. Partial 

 section of the gray part of the spinal cord (even if it be cut at 

 two or three different levels) does not destroy the sensation of any 

 local area of skin, showing that the delicate felt-work of nerve 

 fibrils in the gray substance can conduct the impulses in many 

 directions, so that even when a considerable number of the 

 ordinary routes are blocked by section of fibrils and destruction 

 of the cells at the part cut, the neighboring channels can carry 

 on the work, so that after a little time the sensory impulses are 

 carried from all parts of the skin to the brain without delay. 



It has already been pointed out that the function of any given 

 nerve fibre depends on the function of its terminals. The fibre 

 itself is merely a conducting agent. In somewhat the same way 

 the functions of any given nerve cell must depend on the number 

 and character of its connections. If it be attached to a motorial 

 end-plate in a muscle, it can only be an exciter of impulses that 

 give rise to motion : if it be connected only with a sensory termi- 

 nal, it can only be a receiver of sensory impulses. But, in the 

 gray matter of the spinal cord, and still more so in that of the 

 cerebral cortex, we may assume that all the cells are in more or 

 less intimate connection with innumerable other cells. In fact, 

 we must imagine that the whole of the gray matter of both cord 

 and brain is interwoven into a complex felt-work of fibrils and 

 cells, which in no part are isolated from the rest, but that all the 

 elements form a continuous system. 



