222 TWENTY-FIRST LECTURE. 



be at last composed. Gerlach subsequently came to a dif- 

 ferent conclusion. According to him, the terminal ramifi- 

 cations of this system of processes unite into a narrow, fine 

 net-work, from which the nerve fibres arise by the combi- 

 nation of the thinnest filaments. The last-mentioned investi- 

 gator absolutely denies that the proper cells of the posterior 

 cornu have axis-cylinder processes. A fundamental ana- 

 tomical difference is, therefore, maintained for the motory and 

 sensory cells. I trust neither the statements of Deiters or 

 Gerlach. With the present accessories we can, unfortunately, 

 obtain no certain result. Everything remains a conjecture. 

 The manner of arrangement of the bundles of the posterior 

 sensory root is, unfortunately, still more complicated than 

 that of the anterior, and the fibres become considerably nar- 

 rower on their entrance into the gray substance. Our knowl- 

 edge is, accordingly, here still incomplete. 



The greater portion of the bundles of fibres appear to main- 

 tain a chaotic course through the posterior columns, to later 

 pas^ from the side into the convex part, or portion turned 

 inwards, of the posterior cornu (k). The substantia gelatinosa 

 Rolandi is here seen to be permeated by the finest nerve 

 fibres. The latter are said to pass in part to the base of the 

 posterior cornu, part of them reaching the Clarke's columns. 

 Furthermore, still other bundles of fibres pass over the latter, 

 more in front. Bundles of sensory fibres may even enter 

 both commissures. 



We now come to the question, what do the white longitu- 

 dinally disposed systems of columns signify ? 



That they do not represent the bent fibrous masses of the 

 roots of the spinal cord which pass to the brain, as was as- 

 serted at an earlier epoch, requires no further discussion 

 after what we have learned concerning these roots. 



According to the views of Deiters, these vertical bundles 

 of white fibres come from one transverse plane of the gray 

 substance to subsequently sink into another. The roots of 

 the spinal cord terminated, therefore, in the ganglion cells, 

 and the latter sent off, as a simplified continuation, these ver- 



