256 C. JUDSON HERRICK 
The corpus striatum of the frog is in an exceedingly rudimen- 
tary condition, but it is a true striatum (paleostriatum), that is, 
it is a portion of the lateral wall of the cerebral hemisphere 
relatively free from olfactory influence. The ventrolateral 
olfactory tract passes it by toconnect withits own specific terminal 
nucleus farther caudad in the amygdala. 
In urodeles, on the other hand, secondary olfactory fibers reach 
all parts of the lateral wall of the hemisphere, including the 
H. 2114-1-2-5> 
Fig. 34. Horizontal section through the hypothalamus of adult Amblystoma 
tigrinum, from the same specimen as figure 25. Golgi method. X12. The 
section passes through the nucleus of the dorsal olfactory projection tract, 
which is filled with a dense neuropil of fine fibers, which extend caudad through 
almost the entire length of the pars ventralis hypothalami. The nerve fibers 
of the saccus vasculosus in the thin roof of the infundibulum and of the pars 
nervosa of the hypophysis are richly impregnated. Other preparations: show 
that these nerve fibers connect with the hypothalamus, some through the mem- 
branous roof of the infundibulum and some through the floor and side walls, and 
that they extend forward into the region here filled by neuropil from the nucleus 
of the olfactory projection tract, but mostly farther lateral and caudal. 
distribution area of the lateral forebrain bundle in the ventro- 
lateral quadrant. There is, therefore, neither a true corpus 
striatum nor a true amygdala in the urodele, but a relatively 
undifferentiated area in the ventrolateral quadrant which retains 
some of the characteristics of the lateral olfactory nucleus which 
primitively occupied this region, and at the same time has 
acquired, under the influence of its ascending non-olfactory 
connections, the character of a common primordium of both the 
corpus striatum and amygdala. 
