MAUTHNER’S CELL 97 
the descending systems from the cerebellum. The fact that the 
nucleus discharges directly into the motor nuclei makes this sen- 
sory connection a short circuiting of the sensory path and is 
interpreted as an adaptation for rapid reflexes. 
Miiller’s cells. These cells, which I am treating separately from 
the rest of the nucleus motorius tegmenti merely for the sake of 
clearness, differ from their fellows in three ways: they are larger, 
the cell body lies dorsal to the fasciculus longitudinalis lateralis 
just under the acoustic decussation and they are confined to the 
levels of the acoustico-lateral nuclei (figs. 2 and 4). Some of 
them have, in addition to the ventral dendrites, a short lateral 
dendrite. These cells are fairly constant in number and position 
with relation to the subdivisions of the motor tegmental nucleus; 
those near Mauthner’s cell are perfectly constant. The left side 
of figure 4 shows a reconstruction of one of the Miller cells of 
the pars postmauthnerea and one of its companions appears on 
the right side. (There are three close together at this level.) It 
is clear from the figure that the receptive field of this cell is the 
same as that of the other cells of the group except that it is more 
intimately related to the decussating acoustico-lateral fibers, by 
means of the lateral dendrite. The distribution and relative size 
of the Miiller’s cells may be seen at a glance in figure 2 where 
they are indicated by solid dots on the right side. It is clear 
that those in the four rostral groups of the nucleus motorius 
tegmenti, where the VIIIth and lateral line roots and secondary 
fibers are most numerous, are the largest and in these only can 
the lateral dendrites be identified. The Miiller cells are the lar- 
gest of their group (figs. 8-9, where all of the cells are taken from 
the pars superior). The caudal end of the pars suprema is an 
exception (p. 96). Like other cells of the nucleus, their axones 
enter the fasciculus longitudinalis medialis, within which most of 
them descend, but some bifurcate into ascending and descending 
rami. These axones are the largest found in the oblongata, with 
the exception of the Mauthner’s fibers. Some cross at once, as 
the Mauthner’s fibers do, others descend a short distance before 
crossing, and still others give off crossed collaterals from time to 
time. Many, but not all, surround Mauthner’s fiber in the bundle 
