468 THE BRAIN OF MAMMALS, BY TH. MEYNERT. 



the whole of the anterior columns appear uniformly dense 

 whilst the lateral columns for the most part do not acquire 

 their homogeneous medullary appearance until as low as about 

 the middle of the medulla. 



The pes of the fillet proceeding from the testes collects the 

 fasciculi of this medullary fan, so that they present as far as the 

 level of the origin of the facial nerve a nearly annular trans- 

 verse area (figs. 252 and 253, S), which includes a compact 

 ;mass of cells of such a calibre as may be found even be- 

 tween the fasciculi of the fillet while they still cover the 

 superior peduncle. We cannot agree with Stilling in naming 

 these cells gelatinous substance, since they exceed the cells 

 of the latter substance in size, being 30 ju in length and 12 /j. in 

 breadth. 



From the uppermost planes of origin of the nervus facialis, 

 onward, the pes of the fillet is no longer recognizable by the 

 inclosure of this compact mass of nerve corpuscles, and only 

 contains a few scattered cells distributed through its substance. 

 Still, however, in its further course, it is in no way intermixed, 

 as I formerly supposed, with the transverse section of the 

 ascending roots of the fifth pair (fig. 253, Q, on the right side ; 

 figs. 254, 257, 258, $). Transverse sections of the medulla ob- 

 longata, in which the prolongation of the fillet of the testes is 

 exhibited, show, on the contrary, that the pes of the fillet ex- 

 tends as the most external fasciculus of the lateral column into 

 the spinal cord (Stilling), and is applied in the pons and me- 

 dulla oblongata first to the roots of the facial (fig. 254), and below 

 this point immediately to the transverse section of the ascending 

 .roots of the fifth. And whilst the transverse section of this 

 root includes the gelatinous substance continuous with the 

 f caput of the posterior cornu of the spinal cord, and loses 

 itself in its cells, the prolongation of the pes of the fillet is 

 applied in the spinal cord to the caput of the posterior cornu. 

 .At the inferior extremity of the medulla it may be well seen 

 .how the latter exchanges its earlier investment of the roots of 

 the fifth for the lateral and posterior columns which remain in 

 juxtaposition with it throughout the whole length of the spinal 

 cord, because the transverse section of the fine fibres of the 

 fifth always appears, on account of the small quantity of 



