969 
the oblongata. When most developed this side wall is almost reached 
(figs. 4, 5, and 6). 
The medial out-grown portion frequently shows gaps, so that the 
number of cells differs greatly in successive sections. Still more so 
is this the case with the lateral part of the nucleus which in general 
is also much looser, sometimes we see a more or less horizontally 
running row of cells, arranged in a double row, then again the 
row is broken and one or two tiny groups of cells can be seen lying 
laterally. The maximum number of cells contained by the nucleus is 
here 100. in this region the base of the LV ventricle is fairly flat, 
and this can be better seen in a frontal direction. Simultaneously 
the nucleus stretches itself out, and the medial out-growth and the 
lateral pointed part of the nucleus come to lie in one line. Further 
frontally the whole diminishes in size, and very laterally, though 
even more centrally, there is a small group containing 12 —16 cells, 
sometimes arranged in two rows, which nearly touch the side wall 
of the oblongata. The cell-type and the occasional occurrence of 
connecting cells with the main nucleus establish the identity of this 
group. Of this elongated vagus nucleus the tail-end first disappears 
and then the dorsal portion of the thickened medial part. Of the 
rest a more central group of scattered cells remains longest. 
Nucleus ambiguus. Of the nucleus ambiguus in Phoeaena | have 
Fig. 5. Phocaena communis. 
a. Ambiguus. 
b. Connection between anterior horn and dorsal motor vagus nucleus. 
v. Anterior horn. 
