THE AMYGDALA IN AMPHIBIA Aut 
5. In some urodeles the supposed primordium of the vomero- 
nasal organ sends nerve fibers to the accessory olfactory bulb, 
which also receives fibers from other parts of the nasal sac and is 
therefore not the exact equivalent of the vomeronasal formation 
of the frog. There is a ventrolateral olfactory tract whose 
fibers arise from the accessory olfactory bulb and also from other 
parts of the bulb and, accordingly, are not specifically related to 
the vomeronasal organ, as in the frog. 
6. The ventrolateral area of the urodele cerebral hemisphere 
comprises an undifferentiated strio-amygdaloid primordium in 
which the fiber connections described above as characterizing 
the corpus striatum and amygdala, respectively, of Anura are 
inextricably mingled. This is termed the ventrolateral nucleus 
of the hemisphere. The hypothalamic connection of this nucleus 
(olfactory projection tract) is large and well defined. 
7. In both Urodela and Anura the hypothalamic nucleus of 
the olfactory projection tract is in functional connection with the 
septal areas through the medial forebrain bundle, with the dorsal 
part of the thalamus through the tractus thalamo-hypothalamicus 
cruciatus, probably with gustatory and other visceral systems 
of the hypothalamus, and possibly with the pars nervosa of the 
hypophysis. 
8. The lateral wall of the amphibian cerebral hemisphere is 
derived from the lateral olfactory area of more primitive verte- 
brates. The course of differentiation of this region has been 
largely determined by the penetration into it of ascending dience- 
phalic fibers of two systems: 1) somatic fibers from the dorsal 
part of the thalamus through the thalamic projection tracts, 
and 2) visceral fibers from the hypothalamus through the 
olfactory projection tracts. The first factor has dominated the 
further differentiation of the striatal and neopallial complexes; 
the second that of the amygdala and pyriform-lobe complexes. 
9. The olfactory system in all vertebrates has a twofold func- 
tional rdle: 1) visceral or interoceptive in relation with the 
selection and digestion of food, and 2) somatic or exteroceptive 
in relation with the adjustment of the organism to environmental 
conditions. With the opening of the posterior nasal aperture 
