EESTEVEN 0>' THE ANATOMY OF THE SPLS'AL CORD 379 



may also be seen to become continuous after alterijig tbeir course. 

 A large number of these transverse fibres approach the surface in 

 fissiires which contain connective tissue, and admit the passage of 

 vessels from the pia mater of the surface. Within the grey substance 

 they may be ti'aced in connection with the roots of nerves, with the 

 processes of the multipolar ceEs, and with the fibres which form the 

 commissures. 



The oblique fibres may be regarded as intermediate between the 

 transverse and the longitudinal ; they form the deeper strata of the 

 cord, lying nearer to the grey matter from which they proceed up- 

 wards and downwards, becoming longitudinal after running a variable 

 distance. 



The longitudinal fibres constitute the greater portion of the mass 

 of the white columns ; they are the more superficial, and run nearly 

 parallel to each other. 



Dean describes four principal courses of the longitudinal fibres : — 

 1st, obliquely upwards and inwards, penetrating sooner or later into 

 the grey substance : 2nd, fibres which may be slightly oblique at 

 starting, but soon assume a directly transverse course, sometimes 

 varying this by slightly a-scending or descending ; these fibres ajre 

 mostly of the finest sort : 3rd, fibres which enter the posterior column 

 at various angles, but very soon bend roimd, often at quite a sharp 

 angle, descending in a coiirse more or less oblique : -Ith, fibres which 

 are looped or recurrent, seeming to unite both ascending and descend- 

 ing fibres. Besides these four classes, the first three of which have 

 ah'eady been noticed by Stilling, Dean observes, " every variety of in- 

 termediate course will be fovmd, the bimdles of fibres being braided 

 together in most complex manner." " The anterior and lateral 

 columns, apart from the anterior roots, are only partially derived 

 from the cells of the anterior and posterior cornua, soine of the white 

 longitudinal fibres seeming to be direct continuations of the posterior 

 roots, after these have passed through the grey substance ; the poste- 

 rior columns are composed almost exclusively of the posterior roots, 

 a few fibres appearing to be derived from cell processes coming from 

 the large cells, situated on the margin of the posterior cornu : what 

 coui'se these fibres take after lea\Tug the grev substance, I have 

 been luiable to determine definitely." — p. 10. 



Stilling also points out that the longitudinal fibres do not all follow 

 a parallel course, but that many, after a longer or shorter extent, bend 

 in other dii'ections ; but whether all or only some are thus diverted, 

 and whether others continue to follow the v^hole length of the cord, 

 he has not determined. Sometimes horizontal fibres are traceable 

 into the roots of the nerves. The oblique fibres he describes, simi- 

 larly with ]\Ii'. Lockhart Clarke, as passing upwards and downwards, 

 and in one of his plates gives an illustration of their crossing one 

 another. The transverse fibres. Stilling remarks, ai'e more numerous 

 where the larger nerve roots arise. Their course is not always in 

 exactly the same plane, neither are they always straight, but present 

 N. H. K.— 1S62. 2 D 



