94 GEORGE W. BARTELMEZ 
trace; most of them are delicate and doubtless go only a short 
distance rostrally or caudally. Some, however, can be seen en- 
tering the fasciculus longitudinalis medialis, here bifurcating and 
the stronger ramus ascending through the oblongata. 
Pars intermedia. This division of the nucleus extends through 
the inferior part of the facial lobe, from which the secondary 
bundles pass ventrally into the secondary gustatory tract. Fig- 
ure 2 shows it divided into two parts, the more caudal one has 
the same relation to the facial lobe as the inferior division has to 
the vagal lobe. Here too tactile impulses (from the substantia 
gelatinosa) reach it, together with the gustatory impulses. The 
relations with the external arcuates from the ventral acoustic 
nucleus are also well marked, as appears in figure 5. ‘The superior 
part of the group is more intimately related to the acoustico- 
lateral system, numerous secondary fibers of which cross at this 
level; it has become in fact the dominant connection of the motor 
tegmental nucleus. The cells of the pars intermedia are larger 
and have more prominent ventro-lateral dendrites than are found 
at more caudal levels. 
Just rostral to the pars intermedia (fig. 2), is a group of about 
six large cells whose dendritic field is identical with that of the 
small inferior VIth nucleus and both are reached by numerous 
fine fibers from the acoustic nuclei. 
The four most rostral groups of cells extend through the height 
of the acoustico-lateral decussation and are most intimately as- 
sociated with this system. ‘There are more and larger cells and 
a denser neuropil in these groups than in any other part of the 
tegmental nucleus and the axones of the large cells are mostly 
descending. 
The pre-mauthnerian and post-mauthnerian groups (P.PreM. 
and P.Post M.., fig. 2) are so closely related to Mauthner’s cell that 
their dendritic fields are identical respectively with the superior 
and inferior ventral dendrites of that cell (p. 103). Their con- 
nections can best be taken up in connection with the discussion 
of Mauthner’s cell (p. 104). In addition it should be noted that 
the posterior end of the post-mauthnerian nucleus has the same 
field as the large superior VIth nucleus. As is shown in figure 2, 
