366 OLIVER S. STRONG 
garded as the equivalent of the more caudally located left arcuate 
nucleus, there may not be any marked inequality between the 
right and left nuclei. The right nucleus s near the pons, though, 
and may possibly be simply a part of the pons nucleus (‘‘nucleus 
precursorius pontis”’). The asymmetry in the inferior olivary 
nuclei might be due to obliquity of the section but subsequent 
sections (see below) reveal an enormous asymmetry in these 
nuclei involving both the principal and accessory nuclei. 
Laterally and dorso-laterally to the left olivary nucleus and 
lying next the periphery are aberrant pyramidal fibers (figs. 
8, 9, 10 and 11) which detach themselves from the left pyramid 
just cephalad of the olive (fig. 11) and rejoin the pyramid just 
caudad to the same. The bundle of fibers cut obliquely and 
lying near the periphery ventro-lateral to the left olivary nucleus 
in figure 7 is an aberrant bundle of this character which rejoins 
the pyramid a short distance below this level. Such aberrant 
fibers do not separate from the right pyramid but bundles can 
be seen (figs. 8 and 9) lying laterally to the atrophic olivary 
nucleus. ‘The complete separation on the left is evidently due 
to the large left olivary nucleus and this difference is one of a 
number of peculiarities in the present case which illustrate the 
influence of mere spatial accommodation in determining the 
positions of various tracts and nuclei. 
Sections through the lower and middle olivary levels of the 
bulb, and through the hypoglossal nucleus (fig. 8) display very 
strikingly the inequality in the development of the right and 
left inferior olivary nuclei. The principal right olivary nucleus 
is a U-shaped nucleus ranging from about one-third to one-fifth 
the area of the left nucleus. The accessory olivary nuclei show 
the same great reduction in size. Examination of the series 
of sections through the olives shows that the caudal part of the 
right principal olivary nucleus is less atrophied than the cephalic 
part. This is shown by the fact that it extends nearly as far 
caudad as the left and its caudal part is the largest part. Fur- 
ther cephalad it diminishes in size and ends some distance caudad 
of the cephalic end of the right nucleus. The right medial ac- 
cessory olivary nucleus is about as well developed as the right 
