ON THE CENTERS FOR TASTE AND TOUCH IN THE 

 MEDULLA OBLONGATA OF FISHES. 



BY 



C. JUDSON HERRICK. 



(Studies from the Neurological Laboratory of Denison University, No. XIX.) 

 With Fifteen Figures 



It is now generally recognized that in the medulla oblongata of 

 all vertebrates there is a clearly defined longitudinal differentia- 

 tion into four zones, somatic motor, visceral motor, somatic sen- 

 sory and visceral sensory. The somatic sensory is the cephalic 

 continuation of the cornu dorsalis of the spinal cord and includes 

 the funicular nuclei, spinal V tract and its associated substantia 

 gelatinosa Rolandi and sensory V nucleus, the tuberculum acus- 

 ticum and its derivative, the cerebellum, together with the periph- 

 eral nerve roots associated with these structures. The visceral 

 sensory zone includes the fasciculus solitarius of mammals and birds 

 and the associated peripheral roots and gray centers. In the Ich- 

 thyopsida the equivalent structure is the fasciculus communis and 

 the associated gray, comprising the facial and vagal lobes and 

 their prolongations caudad into the spinal cord and cephalad into 

 the mid-brain. The somatic sensory column includes the un- 

 specialized centers for touch and their specialized acustico-later- 

 alis derivatives. The visceral sensory column likewise includes 

 unspecialized centers of general visceral sensation and specialized 

 derivatives for taste. 



Between these somatic and visceral primary centers there is very 

 little direct anatomical connection, their morphologic independ- 

 ence, in fact, being one of the most striking features of the me- 

 dulla oblongata, especially in lower vertebrates, where anatomical 

 continuity would be expected if these two systems were phylogen- 

 etically related. 



Certain fishes which possess functional taste buds in the outer 

 skin, notably the siluroids (Ameiurus) and some gadoids, have 



