6 Foster, Physical Basis of Psychical Events. 



with the substance of the muscular fibre. The nature of 

 an afferent nerve fibre is not so obvious. If we take a 

 fibre of the auditory nerve, we find that it begins as 

 a branched set of delicate filaments surrounding an 

 auditory epithelial cell. These unite into a fibre which, 

 becoming clothed with myelin, has in this and other 

 respects at least a great resemblance to an axon. The 

 fibre, pursuing its course, passes into a nerve cell 

 of the so-called spiral ganglion, entering at one pole, 

 while from the opposite pole of the cell proceeds a nerve 

 fibre, an indubitable axon, which, making its way to a 

 particular part of the brain, ends after the manner of an 

 axon, by linkage with another nerve cell. The fibre which 

 joins the nerve cell in the spiral ganglion to the brain is, as I 

 just now said, indubitably an axon; the nature of the fibre 

 which joins the auditory epithelial cell to the nerve cell of 

 the spiral ganglion has been debated. It has been urged 

 that it is an axon because it is clothed with myelin ; for, in 

 the case of the nerve cells lying within the central nervous 

 system, the part which is clothed with myelin is always an 

 axon ; the dendrites are never so clothed. But all axons are 

 not clothed with myelin ; on the other hand, within the 

 central nervous system, where the dendrites are devoid of a 

 myelin coating, no instances are known of a dendrite being 

 prolonged as a fibre to a considerable distance from the 

 nucleus or main body of the cell to which it belongs, yet 

 this is the case with this part of the auditory fibre, if 

 we consider it as a dendrite of the nerve cell in the spiral 

 ganglion. Moreover, at its beginning as an arborescence 

 round the auditory epithelial cell, this fibre has the 

 appearance of a dendrite; for that epithelial cell may 

 be regarded as a potential nerve cell, without either 

 axon or dendrites, as are all nerve cells at an early stage 

 of their existence. Hence we may regard the fibre, the 

 nature of which we are discussing, as the dendritic moiety 



