HeRRICK, Medulla Oblongata of Fishes. 407 



sidering, each of the two primary sensory functional zones con- 

 tains, in addition to the primary terminal nucleus of the related 

 nerve roots, very important coordination centers. In the visceral 

 zone the nucleus intermedins facialis et vagi, as described in 

 Ameiurus (Herrick, '05) is such a coordination center, putting 

 the primary visceral centers of the facial and vagal lobes into func- 

 tional relation with the formatio reticularis and thence with the 

 motor cerebral nuclei. It is well known that the primary somatic 

 sensory (tactile) center of this region, the substantia gelatinosa 

 Rolandi, is similarly in functional relation with the formatio reticu- 

 laris (Cajal, '96). 



There is further a broad connection of medullated fibers, as 

 shown by Weigert-Pal sections of Ameiurus, from the spinal V 

 tract to the facial lobe which seems to be unique. These tracts, 

 which appear to be collaterals of the trigeminus root fibers, plunge 

 through the substantia gelatinosa Rolandi to end among the intrin- 

 sic neurones of the deeper layers of the facial lobe. When we 

 remember that the facial lobe of Ameiurus receives only those root 

 fibers of the facial nerve which connect peripherally with taste buds 

 in the outer skin (Herrick, '01), and that the spinal V tract con- 

 tains root fibers of the trigeminus which conduct tactile sensibility 

 from the same areas of skin in which these taste buds occur, it 

 appears highly probable that the fibrous connection between the 

 spinal V tract and the facial lobe is for the purpose of effecting a 

 correlation of the two diverse modalities of cutaneous sensibility 

 which enter the brain by the V and VII nerve roots. The intrinsic 

 neurones of the facial lobe must be regarded as the coordinating 

 cells. 



The facial lobe of Ameiurus, then, is not only a primary end- 

 station for the gustatory root of the VII nerve, but it is also a cor- 

 relation center for these fibers and for collaterals from the tactile 

 root of the V nerve. Its intermediate nucleus receives neurites of 

 intrinsic neurones which are doubtless in relation with both types 

 of root fibers. It also receives directly a large fascicle of gustatory 

 VII root fibers. 



The nucleus intermedins of the vagal lobe is also a coordination 

 center, though not of exactly the same type. The vagal lobe itself 

 receives no direct tactile root fibers from the spinal V tract, nor 

 were any such fibers observed to reach its nucleus intermedms. 

 The latter nucleus does, however, receive unmedullated neurites 



