70 Bulletin of Laboratories of Denisoti University. [Voi. xiii 



(Fig. 3, lower figure). It lies cephalad, dorsad and mesad of 

 the motor V nucleus, the long dendrites of some of whose cells 

 pierce it and come into relations with some of the termini of 

 the gustatory fibers (Figs. 21 and 23). The motor V nucleus 

 is very large in these fishes and extends far cephalad and dors- 

 ad in intimate relations with the termini of the secondary gus- 

 tatory tract. The dendrites of these motor cells spread out 

 widely in every direction and are not directed ventro-laterad so 

 generally as in the case of the motor nuclei of the VII, IX and 

 X nerves. In fact, the greater part of them take the opposite 

 course, as figured, into the caudal part of the secondary gusta- 

 tory nucleus and the adjacent substantia reticularis grisea. 



This fact, together with others of similar import, suggests 

 the morphological interpretation of this secondary terminal 

 nucleus; viz., that it is merely a specialization from the sub- 

 stantia reticularis. C.ajal ('96, p. 128) has confirmed the view 



■Fig. 20. Parasagittal section througli tlie brain of the spotted sucker, Min- 

 ytrema melanops (Raf.). GoLGi method. X 12. 



The sketch is designed to illustrate the course of the ascending secondary 

 gustatory tract and the connections of its terminal nucleus. The plane of the 

 section is slightly oblique so that the caudal end and the ventral side are nearer 

 the median line than are the cephalic and dorsal borders. The figure is a com- 

 posite, made by outlining one section with the camera lucida and filling in the 

 details from this section and the three sections of the same series on each side 

 immediately adjacent, omitting irrelevant detail. The features introduced are 

 schematized as little as possible. The vsrhole course of the ascending secondary 

 gustatory tract from the facial lobe is shown. The origin of the tract from the 

 vagal lobe lies farther lateral. 



b., tract between secondary gustatory nucleus and n. lateralis valvulae ; 

 com.h., commissura horizontalis, Fritsch ; coin.r. VII, communis (gustatory) 

 root of the facialis; desc.sec.X, descending secondary gustatory tract from the vag- 

 al lobe ;y"./.w., fasciculus longitudinalis medialis ; inf.lob.lat., lateral lobule of in- 

 ferior lobe (hypoaria, C. L. Herrick) ; inf. lob. m., median lobule of inferior lobe 

 (mammillare, C. L. Herrick) ; n.cort., nucleus corticalis, Fritsch ; n.IX, motor 

 nucleus of the glossopharyngeus ; «./aA, nucleus lateralis valvulae; n.rot., nu- 

 cleus rotundus, Fritsch ; m.jA, nucleus subthalamicus, C. L. Herrick; n.V., 

 motor nucleus of the trigeminus; n.VII, motor nucleus of the facialis; r.X.s., 

 sensory root fibers of the vagus; sec.gust.t., ascending secondary gustatory 

 tract from the facial and vagal lobes ; tr.l.h., tractus lobo-bulbaris ; tr.t-c, tractus 

 tecto-cerebellaris ; tr.t.lob., tractus tecto-lobaris, Johnston (commissura ventralis, 

 C. L. Herrick). The area marked «.y«;»V«// contains also the inferior second- 

 ary gustatory nucleus. 



