Her RICK, Gustatory Pat J is in Pis lies. 403 



facial lobe represent the positions of some of the larger of these 

 rosettes. Superficially there is a layer of chief gustatory neu- 

 rones of the same general form as those of the vagal lobe (Fig. 

 17), whose neurite springs from the tip of a dendrite and passes 

 at once into the secondary gustatory tract. The peripheral 

 gustatory neurones enter by the communis root of the facial 

 nerve (= dorsal geniculate root of the trigeminus, Mayser = 

 portio intermedia of Wkisberg in human anatomy) and pass 

 back to the lobe as a huge tract of heavily meduUated fibers 

 close to the median line, constituting the pre-vagal portion of 

 the fasciculus communis of Osborn (^ fasciculus solitarius of 

 mammals). Entering the lateral border of the facial lobe, it 

 spreads out in many strands in the superficial layer among the 

 dendrites of the chief gustatory cells (cf. Figs. 5, 16 and 20). 

 These endings are thick, loosely branched arborizations of wide 

 extent. One of the simpler forms of these endings is impreg- 

 nated in Fig. 18 en the right side. 



There is no well defined motor layer of the facial lobe cor- 

 responding with that of the vagal lobe, but the ventro-lateral 

 portion along the line of attachment to the oblongata is of dif- 

 ferent structure from the rest and will be termed the intermedi- 

 ate zone, or 7incleus intennediiis facialis. It contains rather 

 large neurones whose dendrites spread widely through the whole 

 lateral part of the facial lobe and whose neurites reach the sub- 

 stantia reticularis (Figs. 18, a and 17, a and 8). Here they 

 reach directly the dendrites of the motor VH and less immedi- 

 ately those of the motor V, IX and X nuclei. This is the main 

 pathway for short reflexes from the facial lobe to the oblongata. 

 The absence of a motor layer in the facial lobe which gives rise 

 directly to motor root fibers, like that in the vagal lobe, is to 



a, neurone of the intermediate zone ; asc.s.g.t., main ascending secondary 

 gustatory tract ; com.r. VII, communis (gustatory) root of the facialis ; f.Lm., fas- 

 ciculus longitudinalis medialis ; n.mot. Vll.d., dorsal part of motor VII nucleus ; 

 n.viot. VII. v., ventral part of motor VII nucleus ; mot. VII. r., motor root of 

 facial nerve ; r. IX. sen., sensory root of the IX nerve; r.X.viot., motor root of 

 the vagus ; r.X.s., gustatory root of the vagus ; s.g.t.IX-\-X, secondary gustatory 

 tract from X and IX lobes ; s.g. VII. L, secondary gustatory tract from the facial 

 lobe ; s.r., substantia reticularis ; sp. V, spinal V tract. 



