MEDULLA OBLONGATA OF AMBLYSTOMA 361 



intimately associated with the ascending secondary visceral 

 tract (figs. 5 to 16, tr.v.a.) and give off innumerable delicate collat- 

 erals among the fibers of the latter tract. The indications are 

 that these fine trigeminal fibers effect synaptic connections with 

 the same neurones as do those of the ascending secondary vis- 

 ceral tract, probably for tactual-gustatory correlations (see figs. 25, 

 27,31). 



In figures 9 and 54 are seen scattered coarse arcuate fibers 

 passing from the vicinity of the V root through the stratum album 

 into the ventral commissure. ^Nlany of our preparations suggest 

 that these are crossed sensory root fibers terminating in the motor 

 V nucleus of the opposite side, but the relations are confused here 

 by the presence of other similar fibers which clearly connect with 

 the area acustico-lateralis farther dorsally. 



In a number of longitudinal sections by the methods of Cajal 

 and Golgi I have seen evidence of a few fibers from the VTT root 

 coraplex entering the spinal V root. In one Golgi impregnation 

 such a fiber is clearly defined for a long distance. This fiber bifur- 

 cates into ascending and descending branches, both of which enter 

 the spinal V root. These fibers probably represent the general 

 cutaneous component of the facialis described by Norris ('13j p. 

 285) in Siren, though I have not succeeded in following them 

 peripherally or recognizing their ganglion, and my observations 

 are so few as to requu'e further control. 



Fibers of the general cutaneous system enter the oblongata by 

 two of the vagus roots (see p. 351) and immediately divide into 

 ascending and descending branches accompanjdng the spinal V 

 fibers (figs. 16 and 48). In the frog Wallenberg ('07) finds that 

 spinal V root fibers descend as far as the eighth spinal segment. 



The mesencephalic V root. I have previously recorded some 

 observations upon the central course of this root in Necturus and 

 Amphiuma ('14, pp. 10 and 14). In these species I found that 

 the fibers of the mesencephalic V root pass forward to the tectum 

 in company with the fibers of the tractus spino-tectalis to connect 

 with the cells of the nucleus magnocellularis tecti, chiefly of the 

 same side but partly of the opposite side, the latter fibers crossing 

 in the decussatio veli in company with those of the cerebellar 



