420 journal of Comparative Neurology and Psychology. 



Cajal, receives the descending sensory root of the vagus and is 

 chiefly concerned with unspecialized visceral impressions. The 

 next is the vagal lobe, which includes both unspecialized and gusta- 

 tory centers, the taste fibers coming from within the mouth. 

 Finally, the facial lobe is a neomorph concerned exclusively with 

 gustatory impressions from the outer skin. 



In the somatic zone the dorsal cornu gives rise directly to the 

 spinal nucleus of the trigeminus and farther cephalad to the sub- 

 stantia gelatinosa Rolandi, while the adjacent formatio reticularis 

 grisea is enlarged to form the median and lateral funicular nuclei. 



The commissura infima of Haller is a very complex structure. 

 It has two main divisions; (i) a visceral part associated with the 

 commissural nucleus of Cajal, and (2) a somatic part, which is 

 chiefly a commissure of the funicular nuclei. Associated with the 

 latter is a somatic commissural nucleus, not hitherto described. 



The centers for unspecialized visceral sensation and for taste 

 fibers arising within the mouth have no direct connection with the 

 somatic sensory nuclei; but the facial lobe, which receives gusta- 

 tory sensation from the outer skin, sends a strong tract downward 

 to end in the two funicular nuclei and farther caudad into the 

 spinal cord, for the purpose of efl^ecting correlation between the 

 two modalities of cutaneous sensation, taste and touch. 



This descending secondary gustatory tract from the facial lobe 

 is, of course, morphologically a derivative of the visceral sensory 

 division of the medulla oblongata; but it has assumed all of the 

 characteristics of a somatic tract, ending in the somatic sensory 

 centers with the tactile pathways and exciting the same somatic 

 motor nuclei to action in the response, as the latter. That is, a 

 functional adaptation has crossed one of the most rigid morpho- 

 logical barriers in the central nervous system, the barrier between 

 the visceral and somatic sensory systems. 



Denison University. 

 October 13, 1906. 



