400 J. B. JOHNSTON 
lect: into a broad sheet ventral to the large bundle first mentioned. 
This sheet constitutes the medial olfactory tract. It is thick 
where it abuts upon the large lateral tract but spreads as a very 
thin sheet over the ventral and part of the medial surface. This 
tract runs caudad over the ventro-lateral surface of the tuber- 
culum, gradually diverges from the lateral tract and gives diffuse 
fibers to the tuberculum and the parolfactory area. The medial 
tract borders the striatal area in front and below as the lateral 
tract borders that area dorsally. 
Two compact terminal bundles of the medial tract are of 
especial importance. One bends up into the medial wall between 
the tuberculum and the commissures and is distributed to this 
region (gyrus subcallosus) and to the hippocampal formation. 
This is obviously the equivalent of the olfactory tract component 
in the precommissural fornix system of mammals. The second 
bundle continues along the lateral border of the medial tract 
and runs directly caudad to the amygdaloid prominence, where 
it enters the nucleus of small cells hereafter to be described as 
the nucleus of the lateral olfactory tract. This bundle runs along 
with the large bundle which connects the amygdaloid complex 
with the hippocampus through the precommissural system (ol- 
factory radiations of Zuckerkandl or fiber bundle of the diagonal 
band of Broca). 
CORPUS STRIATUM 
‘Under this name will be described the structures which are 
homologous with the chief parts of the corpus striatum in human 
and mammalian brains. Attention has been called to the fibers 
of the crus cerebri which are seen in a depression on the lateral 
surface of the telencephalon. A section at the rostral border of 
this region (figs. 21, 34) shows two great bundles of fibers cut 
in cross section, the lateral forebrain bundle or crus and the 
medial forebrain bundle. The fibers of the crus rise in fascicles 
(internal capsule) scattered through the outer part of the thick 
latero-basal wall to the dorsal ventricular ridge and pallial thick- 
ening. These include somatic sensory fibers and probably also 
fibers descending to the motor centers. The medial bundle 
