COURSE OF NERYE-FIBRES. 



47 1 



gradually diminish, in size, and assume many of the other 

 characters of the fine fibres of the sympathetic system, it 

 is not necessary to suppose that .there must be a material 

 difference in the office or mode of action of the two kinds 

 of fibres. 



Every nerve-fibre in its course proceeds uninterruptedly 

 from its origin at a nervous centre to near its destination, 

 whether this be the periphery of the body, another nervous 

 centre, or the same centre whence it issued. 

 Fig. 128.* 



Bundles, or fasciculi of fibres, run together in the nerves, 

 but merely lie in apposition with each other ; they do not 

 unite : even when the fasciculi anastomose, there is no 

 union of fibres, but only an interchange of fibres between 

 the anastomosing fasciculi. Although each nerve-fibre is 



* Fig. 128. Small branch of a muscular nerve of the frog, near its 

 termination, showing divisions of the fibres, a, into two ; b, into three ; 

 magnified 350 diameters (from Kolliker). 



