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XXVII. — On the Restoration of Co-ordinated Movements after Nerve Section. By 

 Robert Kennedy, M.A., D.Sc, M.D., Glasgow. [From the University of 

 Glasgow and the Glasgow Veterinary College.] (Communicated by Professor 

 M'Kendrick.) (With Three Plates.) 



(Read April 3, 1899.) 



From the point of view of its function, a nerve fibre is a conductor of nervous 

 impulses, and as such is the path of communication between two structures, the one 

 situated in the central nervous system, and the other in the periphery. In the mixed 

 nerve, such as the sciatic, the nerve fibres are distinguished as afferent or as efferent, 

 according as they conduct impulses originating at the periphery, and received by a cell 

 in the central nervous system, or vice versd. It has long since been shown that nerve 

 fibres are capable of conducting impulses in either direction, but normally, from their 

 anatomical connections, the individual nerve fibres are conductors for impulses only in 

 the one or in the other direction. This is proved by the Wallerian method of investiga- 

 tion, as on severance of the posterior spinal root distal to the ganglion only certain fibres 

 degenerate and the conductivity of the nerve only for afferent impulses is lost, while the 

 severance of the anterior root is followed by the degeneration of the remainder with loss 

 of functions depending on efferent impulses. 



But the conception of nerve fibre and its terminals carries us further, and leads to 

 the view that a particular nerve fibre is concerned only with the conduction of impulses 

 from a particular point, e.g., from a particular sensory area of the skin, or, on the other 

 hand, that it is concerned with the passage of impulses from a particular central cell to 

 particular end-organs. The individual nerve fibres are thus viewed not as common con- 

 ductors for impulses originating from different points, but each as a specific conductor 

 for impulses starting in a particular cell, and received at the other end also in a particular 

 cell. Thus a transverse section of a mixed nerve with its innumerable nerve fibres 

 might, if knowledge were sufficiently exact, have each of the latter named according to 

 its origin or distribution. 



It is true that the passage of the nerve fibres between the peripheral organ and the 

 brain is not necessarily continuous, but may be interrupted by the intervention of cells ; 

 but in the modern conception of say the motor neuron the cell body situated in the 

 comua of the cord connects directly with the peripheral organ by means of its neuraxon, 

 whi]e the cell body receives its stimuli from another definite cell, situated it may be in 

 the cortex, by means of the neuraxon of the latter. The individual nerve fibres in a 

 nerve must, however, be regarded as paths for the conduction of impulses each from a 

 definite point to a definite point. 



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