Herrick, Gustatory Paths in Fishes. 439 



veloped, the lobus facialis, which receives all the gustatory- 

 nerves from the outer skin. 



The purpose of this study is to trace the farther course of 

 these gustatory pathways within the brain and in particular to 

 map out the reflex paths for the various types of gustatory reac- 

 tion which have been actually observed in the feeding activities 

 of these fishes. 



Peripheral gustatory nerve fibers (especially those of the X 

 and IX nerves) enter the brain in company with unspecialized 

 visceral sensory fibers from which they can be distinguished 

 within the brain only with difficulty. This mixed system is 

 spoken of as the communis system of nerves and centers. It is 

 probable that the complete analysis of this complex can be 

 made only by the degeneration method. But the comparative 

 method has enabled us to determine with great probability the 

 chief secondary connections of both types of fibers and so to 

 prepare the way for an accurate determination of the gustatory 

 pathways in the human brain, which are at present almost 

 wholly unknown. 



In the cyprinoids and siluroids the primary gustatory cen- 

 ters possess in both the facial and the vagal lobes two types of 

 secondary neurones ; (i) small intrinsic neurones (largely of 

 GoLGi's type II) filling the interior of the lobe, and (2) larger 

 and very highly specialized neurones superficially arranged over 

 the lobes — the chief secondary gustatory neurones. 



The intrinsic neurones serve to diffuse incoming stimuli 

 throughout the substance of the lobes and those with longer 

 neurites effect connections with adjacent motor areas, chiefly 

 by way of the substantia reticularis grisea. These connections 

 are probably very largely for unspecialized visceral sensory re- 

 flexes, as well as for direct response of the mandibular bran- 

 chial and palatal musculature (muscles of the visceral system) 

 to gustatory stimulation, and are probably substantially similar 

 in all vertebrates. 



The chief gustatory neurones of both vagal and facial lobes 

 give rise to the long paths of secondary connection for distant 

 parts of the brain. Their dendrites receive directly the per- 



