Kappers, Teleostean and Selachian Brain. 75 



longitudinal bundle and pass to another complex of short and long 

 paths which many authors consider to belong to the group last 

 described — the tr. thalamo-s pinahs . 



Its fibers are distinguished from the dorsalis fibers only bv a 

 somewhat smaller caliber and lighter color after the Weigert 

 stain, in this respect resembling the sensory tracts of this region 

 more than the motor ones, which have the same appearance as 

 the fasc. long, dorsalis, as I mentioned when treating of the mid- 

 brain. They are present through the whole length of the oblon- 

 gata under and at the side of the last mentioned system and cau- 

 dally their number is greater than frontally. These fibers also 

 seem to increase in the octavus region and doubtless this complex 

 must be considered as composed, like the dorsal bundle, of shorter 

 and longer longitudinal tracts forming a fronto-caudal and a 

 caudo-frontal association system, probably connecting regions 

 situated laterally to the motor column. It certainly does not 

 contain thalamic fibers exclusively in all parts of its course. As I 

 described when treating of the 'tween-brain, its fibers assemble first 

 in the substantia grisea centralis and m a still more lateral region. 



Now, passing to the nerves of the oblongata, I will describe the 

 situation of their roots, their intra-medullary courses and their 

 terminal nuclei and nuclei of origin, some of which I have already 

 mentioned in connection with the frontal tracts. 



The nervus frigrtninus enters the oblongata laterally with its 

 sensory and motor fibers (I.ophius, Fig. Ixxiv, Plate V; Gadus, 

 Figs, xc, xci, Plate VI). The motor root, consisting of thicker, 

 more heavily medullated fibers, originates from the large motor 

 ganglion cells which in the younger Lophms still he mmiediately 

 under the fourth ventricle, but in the full-grown cod are removed 

 downward between the two bundles of the fasc. long, lateralis, 

 as already mentioned when describing that tract. They are 

 situated m a plane which forms with the raphe an angle of about 

 45 degrees and extend backward into the motor facialis nucleus 

 and forward into the ventral cell column which was described 

 when speaking of the cerebello-motor tract. The motor fibers 

 originate partly without decussation, while another part goes 

 through the fasciculus dorsalis and ends in the nucleus of the other 

 side. I have already mentioned that this nucleus has a crossed 

 connection with the cerebellum by means of fibers which run 

 through the fasciculus dorsalis. 



