TRACTUS OLFACTO-TEGMENTALIS 287 
fornix crossing the anterior commissure vertically. On the left 
side appear a larger and a smaller commissural bundle. The 
smaller (bdl. x) is one of the olfactory bundles of the anterior 
commissure which crosses the mid-line independently of the main 
body of the commissure. Crossing these two bundles in a sweep- 
ing curve is a small bundle which runs down into the tuber 
cinereum. When this small bundle is traced rostrad it joinsthe 
smaller commissural bundle (fig. 3). Hence, a small bundle sepa- 
rates from the olfactory commissure, passes over the anterior 
commissure and enters the tuber cinereum. This condition has 
not before been described so far as the writer is aware. 
In the section described there appears beneath the limb of 
the anterior commissure a fair sized bundle almost round in 
transverse section (tr.olf-tegm.). When this bundle is traced ros- 
trad it is found that it intermingles with the olfactory bundles 
of the anterior commissure and has a commmon origin with these. 
This is illustrated in figures 1, 2, and 3. While some fibers may 
enter these bundles from the olfactory tract, there can be no 
doubt that most of the fibers are directly related to the olfactory 
tubercle and adjacent secondary olfactory centers. 
The course of this bundle caudal to the level of the anterior 
commissure is shown in figures 5, 6, 7,8, 9. The bundle is sym- 
metrical on the two sides, but only the left side is drawn. It 
runs along the inner face of the internal capsule and descends 
somewhat into the hypothalamus until it comes to lie between 
the terminal portion of the fornix and the internal capsule (fig. 
7). Beyond the mammillary body it rises again and gains a posi- 
tion dorsal to the medial border of the crus (fig. 8). The bun- 
dle then continues between the substantia nigra and the nucleus 
ruber and divides into several fascicles. These fascicles while 
continuing spinalward turn rather rapidly dorsad and somewhat 
laterad. They become imbedded in small masses of cells and are 
lost just at the upper or anterior border of the pons (fig. 9). 
One fascicle seems to enter the dorsal part of the pontile gray 
(fig. 9). One or two fascicles run much farther dorsad than the 
others, but do not approach so near the brachium pontis. 
