THE VISCERAL AFFERENT DIVISION. 169 



to tactile impulses from the skin and give rise to reflex contractions 

 of the branchial muscles controlling the respiratory movement >. 

 It is inherently probable that a part of the fibers of the long tract 

 to the metencephalic nucleus have general visceral functions, 

 especially as such a tract is present in mammals coming forward 

 from the trunk, where taste organs are out of the question. We 

 must at present suppose that when taste buds were first developed 

 in vertebrates they came to be innervated by the general visceral 

 fibers which already supplied the area in which the taste buds 

 appeared. As the gustatory system came to be more important 

 the long secondary tracts came especially into its service for the 

 reason that these long tracts make possible more complex reflexes 

 adapted to the capturing of food. 



It is in the bony fishes, where the gustatory apparatus has 

 reached an enormous development, that the secondary and tertiary 

 connections of the taste center have been most fully worked out 

 (Figs. 89, 90). Here the secondary visceral tract has the same 

 general arrangement as has been described above. As the gusta- 

 tory elements greatly preponderate in it, we may call it the secondary 

 gustatory tract. Caudally a part of this tract extends into the 

 spinal cord and a part ends in an interior secondary gustatory 

 nulceus adjoining the nucleus commissuralis. Complex rela- 

 tions between this and the adjacent nucleus funiculi (cutaneous 

 center) perhaps enable the animal to correlate tactile with gusta- 

 tory impulses in the control of movements for the capture of 

 food. Cephalad the tract ends in the metencephalic nucleus, 

 which Herrick calls the superior secondary gustatory nucleus. 

 Part of the fibers end in the nucleus of the same side and part 

 cross to the opposite side in a commissure which may be called 

 the inferior cerebellar commissure. This commissure contains 

 also fibers arising from the cells of the secondary nucleus. The 

 nucleus is an enlargement of the gray matter bounding the fourth 

 ventricle laterally and is very rich in cells and in terminal rami- 

 fications of fibers. From this nucleus, in addition to the com- 

 missural fibers, arises a tract which runs to the inferior lobes of 

 the diencephalon. Other fibers from the secondary gustatory 

 nucleus seem to go into the cerebellum and the tectum mcsen- 



