THE AMYGDALA IN AMPHIBIA 255 
IV. MORPHOGENESIS OF THE URODELE STRIO-AMYGDALOID 
COMPLEX 
From the relations .described it is evident that the urodeles 
possess no amygdala as a separate nucleus differentiated from 
the other elements of the ventrolateral part of the hemisphere. 
The fiber connections of the ventrolateral nucleus which forms 
a thickening of the wall in the caudal part of this area show, 
however, that this nucleus combines the functions of corpus 
striatum and amygdala, both in a very unspecialized form, 
that it is, in short, a strio-amygdaloid body. 
inf. 
7 
H. 215 9-2- 2-21. 
Fig. 33 Horizontal section through the most ventral fibers of the postoptic 
commissure of an old larva of Amblystoma tigrinum. Golgi method. X 74. 
The single neuron impregnated lies considerably ventrally of those shown in 
figure 32 and is of different type. As in the other case, the principal dendrite 
extends forward into the decussation of the tractus thalamo-hypothalamicus 
cruciatus; but the axon, instead of passing forward into the olfactory projec- 
tion tract, breaks up into a loose arborization whose longest branches are directed 
caudad. In other preparations of similar larvae fibers connected with the pars 
nervosa of the hypophysis extend forward into this position, and this neuron 
may be the source of such a fiber. It lies ventrally of the nucleus of the olfac- 
tory projection tract, though fibers of that tract may extend into this region. 
Its chief source of excitation is clearly the thalamo-hypothalamic tract, free 
terminals derived from which reach back almost to the caudal end of the hypo- 
thalamus, as shown on the right side of the figure (on the left this neuropil is 
present, but is omitted from the drawing). ‘ 
