258 C. JUDSON HERRICK 
2. Ascending thalamic systems (somesthetic, optic, auditory). 
These came forward originally into the lateral olfactory area, 
thus effecting various somatic-olfactory correlations. This type 
of correlation probably survives to some degree in the mamma- 
lian pyriform lobe and in part of the amygdala. But the corpus 
striatum, and in mammals the neopallium, are largely emanci- 
pated from the olfactory influence. (The striatum is not entirely 
so, as shown by Cajal’s description (’11, p. 723) of fibers arising 
Fig. 35 Diagrammatic horizontal section through the brain of the frog at the 
level of the interventricular foramén, to illustrate the relations of the ventro- 
lateral olfactory tract, the dorsal olfactory projection tract, the amygdalo- 
pyriform tract, and the lateral forebrain bundle. 
from neurons of the cortex of the pyriform lobe and entering 
into the complicated intrinsic neuropil of the lentiform nucleus.) 
3: Ascending and descending hypothalamic connections. This 
is a very primitive connection and apparently originally put the 
non-somatic systems (as the term somatic is used above) of the 
hypothalamus into relation with the lateral olfactory area. 
4. The habenular connections. These are related to the 
olfactory centers of the hemisphere only and so far as known are 
efferent with reference to the hemisphere. 
