434 ELIZABETH HOPKINS DUNN 



('04) in considering that these cells represent the cells of DogieFs 

 Type II (new types III, IV, VIII and XI) and are relay cells 

 within the ganglion. The scattered condition of these cells is 

 against the identification of them with the perikarya of our fibers. 

 The microscopic characters of the non-reactive cells as described 

 by the various observers do not agree with those of the mass of 

 neurones which are supposed to be connected with the function- 

 ing of sensory transmission from the periphery to the spinal cord. 

 I am able therefore to make no suggestions as to the identification 

 of the perikarya under discussion with observed neurones within 

 the spinal ganglia. 



Finally, one physiological finding may be cited in connection 

 with the contention that these are central sensory fibers. It 

 has been noted that sensory stimuli have reached the central 

 nervous system after the dorsal roots no longer function. This 

 occurs in cases of disease of the dorsal roots, but its recognized 

 association with the experimental interruption of function is of 

 more importance to this discussion. The existence of central 

 processes of spinal ganglion neurones may furnish the pathway 

 over which such sensory impulses find their entrance to the cen- 

 tral nervous system. If this pathway exists Kidd's postulate 

 of the occurrence of afferent ventral root nerve fibers of central 

 location is unnecessary. The presence in the dorsal root of aber- 

 rant fibers of efferent function was determined through physio- 

 logical experiment by Horton-Smith in 1897. 



Aberrant medullated nerve fibers have been discovered in 

 many parts of the central nervous system and seem to be as 

 frequent in occurrence as might be postulated from our knowl- 

 edge of the early stages of development of the neurone. Since 

 axis cylinder processes are outgrowths of neurones of tentacle 

 like nature which seek for and are perpetuated by permanent 

 functional connections, it may well be that some of these ten- 

 tacles in the case of spinal ganglion neurones push their way 

 among the embryonic connective tissue structures, and on reach- 

 ing the ventral root outgrowth; follow the matrix thus furnished 

 and arrive at the spinal cord. Such axonic processes as find 



