8 Journal of Comparative Neurology. 



witsch, though they were not followed caudad any distance. 

 The view also that this tract represents the dorsal column in the 

 myel and that its fibers correspond to the sensory fibers of 

 spinal nerves needs not be emphasized. In fishes, teleosts es- 

 pecially, the correctness of this view seems quite evident and 

 has been recognized by Mayser. In higher vertebrates we find 

 this view supported by Kolliker, Gaskell and Turner ; the latter 

 considers the spinal root of the fifth and the solitary tract homo- 

 dynamous, and apparently considers that both together repre- 

 sent the dorsal columns ; Minot regards the tractiis solitarius as 

 continuing in the oblongata the dorsal column of the myel 

 {fasciculus ovalis of the embryo). It is impossible therefore to 

 draw any entirely satisfactory conclusions as to the representa- 

 tive of the dorsal column in the oblongata, since facts of devel- 

 opment in all but mammals are wanting. The homology of the 

 vagal component derived from this system in some lower forms, 

 and of the tractus solitarius,' is involved. Strong considers the 

 fasciculus communis as the homologue of the tractus solitarius. 

 Minot states that the late development of the spinal Vth tract 

 in man interferes with a true comprehension of its value. 



In Aniia (and in certain teleosts at least) not only does this 

 system furnish fibers for the Vth, but also for the Xth, as 

 Strong assumed would be the case. The exit in Aniia of a 

 small portion of the fibers with the VII-VIII appears to be an 

 exceptional condition, though constant in the few brains exam- 

 ined for it. An important point in regard to this tract in Amia 

 (and other Ganoids) is that it is superficial. The enlargement 

 of the dorsal horns caudad of the metatela produces corres- 

 ponding ectal swellings resembling the clavas of the mamma- 

 lian brain, and from these in specimens in which all connective 

 tissue has been removed from the surface of the oblongata, the 

 spinal Vth can be traced. A slight swelling caused by the 

 tract and a difference in color from the surrounding portions, 

 due apparently to the concentration of the fibers, renders it 

 easily distinguishable with the unaided eye. It seems especi- 

 ally prominent in formalin preparations, and can be followed 



