Herrick, Gustatory Paths in Fishes. ^j'j'j 



sis of a single functional system of neurones — the gustatory- 

 system — in types where it reaches its maximum development 

 and is obscured as little as possible by a high development 

 of other systems. These conditions are fulfilled perfectly in the 

 cyprinoid and siluroid fishes, whose brains are uncomplicated by 

 any pathways leading to or from the cortex of the fore-brain 

 and are in the main merely reflex mechanisms, but whose peri- 

 pheral gustatory pathways are more highly developed than in 

 any other vertebrates. 



Section II. The Peripheral Gustatory System in Fishes. 



As is well known, taste buds occur freely scattered over 

 the mucous lining of the mouth and gills of nearly all fishes 

 from the lips to the oesophagus. These are innervated by the 

 VII, IX, and X cranial nerves. Similar taste buds, commonly 

 called terminal buds, occur in the outer skin of some fishes and 

 these also have been recently shown to be gustatory in func- 

 tion (JuDSON Herrick, '04). They are, in all cases where 

 the innervation is known, supplied by the facial nerve. All 

 taste buds in the pharynx and back part of the mouth, then, 

 are supplied from the vagus and glossopharyngeus, those in the 

 front part of the mouth, lips and outer skin from a root of the 

 faciahs which apparently corresponds with the portio intermedia 

 of human anatomy. 



Associated with each of these roots are unspecialized 

 visceral sensory fibers ending by free arborizations in the mu- 

 cous membrane of the mouth cavity, these being very numer- 

 ous in the region of the lower vagal roots and diminishing 

 cephalad. The central connections of these two elements have 

 not as yet been clearly differentiated, and both are provisionally 

 designated the " communis system " of nerves by students of 

 nerve components. With the unspecialized fibers we are not 

 here concerned. The specialized communis fibers related with 

 taste buds, either within or outside the mouth, and the ganglion 

 cells from which they are derived will be termed the peripheral 

 gustatory system of neurones. 



