446 Journal of Comparative Neurology and Psychology. 



region of the funicular nuclei. Here is a commissure which 

 corresponds to the commissura infima Halleri of teleosts and 

 a commissural nucleus which is also present in fishes 

 and which is closely related to the inferior secondary 

 gustatory nucleus of my descriptions. In the mouse 

 the greater part of the primary sensory root fibers of the IX 

 and X nerves appears to end in this nucleus ; in the fishes a very 

 small part, while the greater part of the fibers end in the vagal 

 lobe whose sensory portion is homologous with the dorsal sen- 

 sory nucleus of Kolliker. The commissural nucleus of Cajal, 

 as a primary end-station for the spinal root of the vagus, is 

 homologous with the terminal nucleus of the descending vagus 

 root fibers associated with the inferior secondary gustatory nu- 

 cleus. The latter nucleus is not represented in Cajal's descrip- 

 tions, though I venture the prediction that further study of the 

 mammals will show that it too is represented in the commissur- 

 al nucleus. Cajal finds that the neurites of the cells of the 

 commissural nucleus enter the lemniscus along with secondary 

 tracts from the funicular nuclei (secondary tactile path), and 

 here again the teleostean and mammalian relations are closely 

 parallel. 



His has shown that the fasciculus solitarius, when first appar- 

 ent in the human embryo, lies, like the spinal V, superficially on 

 the lateral border of the oblongata and its deeper adult position is 

 due to the overgrowth of structures from the "Rautenlippe." 

 In teleosts it lies still deeper, as close to the median line as pos- 

 sible. This may be explained by the fact that the fasciculus 

 solitarius as a visceral sensory tract is more ancient than the 

 specialized somatic sensory enlargement (tuberculum acusticum) 

 of this part of the oblongata. The communis VII + IX 

 (= fasc. communis) was therefore passively crowded inward 

 from the primitive superficial position by the over-growth of 

 the tuberculum acusticum (and later by the "Rautenlippe" for 

 the olive) and prevented from passing ventrally by the great 

 ventro-lateral tracts and the secondary mechanism for the tub- 

 erculum acusticum. The spinal V tract, however, being organ- 

 ically connected with the somatic sensory centers here develop- 



