THE NRRVOUS SYSTEM. 415 



Here they divide into separate, slenderer, or thicker fas- 

 ciculi (from 001 — 0-02'") (figs. Ml, s, 141, b), and con- 

 tinuc, each buudle by itself, in a straight course, and with- 

 out any direct connection with nerve-cells, quite through the 

 substantia gelatinosa into the substantia grisea. In this 

 course they follow two directions. One portion of them bends 

 upwards, in a uniform curve, or nearly at a right angle, 

 proceeds in the most posterior part of the substantia grisea, 

 close in front of the substantia gelatinosa in a longitudinal 

 direction, and gradually joins chiefly the posterior column, but 

 in part also the posterior portions of the lateral column, being 

 continued further, as its longitudinal fibres (figs. 141, r, 144, //). 

 A second portion of the sensitive roots (figs. 141, t, 144), 

 penetrates, always in a fascicular form, between the above- 

 mentioned longitudinal bundles further forwards, losing 

 itself in the posterior and in the lateral columns, and also 

 entering the grey commissures. In horizontal sections, the 

 former fibres are frequently very distinct, particularly those 

 going off to the posterior columns (fig. 141, p, q). I have 

 seen them most distinctly in the inferior extremity of the 

 spinal cord, below the lumbar enlargement, where they ran 

 towards the conus medullaris, close up to the grey central 

 nucleus, and did not bend backwards until they reached the 

 posterior columns ; they were also well displayed in the lumbar 

 enlargement, between the substantia gelatinosa and the pos- 

 terior commissure. The horizontal radical fibres, also, which 

 proceed to the lateral columns, are often exceedingly numerous, 

 although much less so, apparently, than those which enter the 

 posterior columns. The connection of the grey commissures 

 with a portion of the sensitive radical fibres, is, as regards the 

 posterior fibres,not difficult to be seen, these fibres, in part, at 

 least, running backwards along the posterior columns, and being 

 continued directly into the fasciculi of the substantia gelatinosa. 

 In the anterior grey commissure, I have also noticed, though 

 not a direct connection with the sensitive roots, still, fibres 

 which, running horizontally in a direction towards the summits 

 of the posterior horns, entered those processes. The com- 

 missural fibres are, besides, connected not only with the 

 sensitive roots, but also, and indeed quite evidently, with the 

 posterior columns, and less distinctly with the lateral ; from the 



