44 THE STRUCTURE OF 



3. In other nerve cells, furnished with many ramifying 

 processes, one long simple process maybe seen (figs. 13, a, 

 14), which is occasionally traceable into direct continuity 

 with the entire axis cylinder of a nerve fibre (D(^iters). 

 This mode of union is now generally admitted to exist, and 

 it is not improbable that nerves so arising are, usually at 

 least, outgoing fibres. Whilst this view cannot be defi- 

 nitely verified, it is a fact that such processes have been 

 found principally in the spinal cord in connection with 

 the nerve cells of the anterior, or motor, regions of its 

 grey matter. 



There is thus some ground for believing that ingoing 

 fibres, in the majority of cases, swell in the posterior spinal 

 ganglia and their analogues into nerve cells (fig. 10) ; 

 that within the larger nerve centres these fibres, which 

 convey ingoing currents, break up into a pencil of ultimate 

 fibrils, and that these ultimate fibrils may be partly in 

 structural continuity with the neuroglia, and partly with 

 the radicles of a much branched nerve process (fig. 12), 

 the divisions of which unite (like the radicles of a vein), 

 till they are gathered into one or more branches directly 

 continuous with the substance of the nerve cell. Such 

 arrangements may suffice to break the force of Ingoing Cur- 

 rents as they impinge upon highly excitable centres ; or 

 their diffusion therein may thus be facilitated, aud as a con- 

 sequence they may be enabled to come into relation with the 

 ultimate ramifications of processes pertaining to several cells. 



On the other hand, there is ground for belioAdng that 

 Outgoing Currents leave the cells of the spinal motor 

 centres by undivided processes, which are directly con- 

 tinuous with the axis-bands of dark bordered nerve fibres. 



Should these su])p()sitions be correct as to the mode 

 in which currents impinge upon the sensory side, and 

 subsequently issue from the motor side of a nerve centre, 



