74 yoiirnal of Comparative Neurology and Psychology. 



association fibers are divided into two bundles (Figs, xcv, xcvi, 

 Plate VI), one of which originates from the dorsal region caudad 

 of the beginning of the fasc. long, lateralis while the other and 

 smaller one arises more laterally and bends down above and around 

 the tr. descendens nervi quinti, after which it joins the more dorsal 

 fibers in their passage through the raphe. 



Now, in Gadus some bundles of the dorsal part of these fibers 

 may be followed into the motor cell colunm after decussation 

 through the dorsal longitudinal bundle. These may be called 

 tr. octavo-motorius cruciatus. This tract arises in the tubercula 

 liniae lateralis in the same way as the analogous cerebellar fibers 

 in the cerebellum, for it forms the most medial bundles of this 

 region. They form a considerable part of the -fibrce arciiatcc 

 internee, or dorsales, which a little farther frontally also include 

 the decussating fibers of the lateral longitudinal bundle, already 

 described. 



This static-motor connection, accordingly, is the continuation 

 of the cerebellar tract described; or rather, conversely, the cere- 

 bellar tract is an extension of this static-motor connection, of more 

 recent origin. This appears from its absence in younger animals, 

 as the cerebellum itself arises late as we know from Schaper's 

 investigations, where its bilateral origin from the lateral wall of 

 the oblongata is described. The static function of these two 

 regions and their general agreement in structure has been abun- 

 dantly confirmed by physiologists and histologists. As far as this 

 connection of the primary center is concerned, I believe that the 

 experiments of Quix on the labyrinth of the sharks may also 

 prove the presence of this simple connection between the octavus 

 region and the motor nuclei, in this case the oculo-motor nuclei, 

 as after stimulation of the labyrinth he observed several immediate 

 ocular movements, as Professor Bolk once demonstrated to me 

 in Naples. 



The presence of fibers, partly uncrossed and partly decussating 

 in the median line of the oblongata, going from the static center 

 backward into the motor nuclei was demonstrated by Bethe by 

 physiological experimentation in his investigations on the loco- 

 motion of Scyllium. Although it would be very interesting indeed 

 to look for further relations between his experiments and those of 

 LoEB and Steiner with the structures described, the scope of my 

 investigations does not allow this and I must now leave the dorsal 



