CENTRAL RELATIONS OF COMPONENTS. 63 



of the fishes are as a whole homologous with the fasciculus 

 solitarius and its related structures (including the sensory 

 IX + X nucleus and the chief sensory vagus roots), ex- 

 cluding motor and general cutaneous elements in both 

 cases. 



(2). In the fishes the pre- and post- vagal fasciculus 

 communis represent the fasciculus solitarius of the mam- 

 mals, though the parallelism is probably not exact. 



(3). The terminal nucleus of the fasciculus solitarius 

 or the "spinal nucleus of the vagus " of the mammals has 

 in the fishes been for the most part absorbed by the lobus 

 vagi. Its caudal portion may persist, however, behind 

 the commissura infima. 



(4). The sensory IX + X nucleus of the mammals is 

 merely a specialized portion of the nucleus of the fascic- 

 ulus solitarius, and, accordingly, is represented with the 

 latter in the lobus vagi of the fishes. 



(5). The transverse fibres of the commissural nucleus 



of Cajal are probably homologous with the fibres of the 



spinal portion of the fasciculus communis, which appear 



in the commissura infima Halleri of the fishes. 



Since this discussion was written and submitted for publication 

 two papers have appeared which have an important bearing upon 

 the homologies proposed. Both Van Gehuchten's researches upon 

 the real origin of the cranial nei-ves {Journal de Netirologie, i8g8) 

 and Bunzl-Federn's paper on the central origin of the vagus {Monats. 

 f. Psychiatrie u. Neurologie, V. , i, Jan., 1S99) give the results of de- 

 generation experiments by the Nissl method after resection of the 

 vagus. Van Gehuchten shows that section of the vagus roots in the 

 rabbit results in chromatolysis of cells throughout the dorsal or chief 

 vagus nucleus. He concludes that this nucleus is wholly motor and 

 confirms this by Golgi preparations. Marchi preparations showed 

 that the sensory nucleus of the vagus is confined to the cells accom- 

 panying the fasciculus solitarius, the "spinal nucleus of the vagus." 

 This would confirm in some degree the results of Forel ('91); but it is 

 significant that Bunzl-Fedem, also working upon the rabbit by the 

 same method, and getting essentially the same anatomical results, 

 does not admit that the dorsal nucleus is entirely motor. 



