OF DEMSON UNIVEkSITY 
75 
Of these tracts especially well marked is a bundle of arching 
fibres passing from this nucleus dorsally toward the nates but apparent- 
ly converging over the aqueduct to the posterior commissure It may 
be suggested that tlris nucleus is centre of co-ordination for the oculo- 
muscular' aparatus. 
The region of the third ventricle. 
Horizontal sections through the lowest portion of the tuber cine- 
reum reveal the same structure as described in the tuber of the alliga- 
tor, /. c., a dense layer of epithelium lining the ventricle, the cells of 
which give rise to long fibres of connective tissue dividing the space 
about the ventricle into compartments in which the very numerous 
flask-shaped cells are closely packed. Tne entire tuber is filled with 
these cells. At its posterior portion are two more densely nucleated 
spots laterad to the lowest point of the fornix tract. 
In higher sections the above-mentioned nuclei and the ceph- 
alad and caudad parts of the fornix tracts become quite distinct. The 
nuclei above described, which may be called the posterior nuclei 
of tlie tuber, give rise to fibre tracts passing dorsad and cephalad lat- 
erally from the cephalad tract of the fornix. About the sides of the 
third ventricle, cephalad is a large, dense nucleus of small cells, the 
anterior tuber nucleus, and in front of this on either side, not far cau- 
dad of the chiasm, is a small tract in cross section. This small bundle 
can be traced dorsad for some distance, but its ultimate course is un- 
known. 
The structure about the third ventricle remains quite constant but 
cephalad from the lamina terminalis is a nucleus of spider-like, slender 
multipolar cells with remarkably long and distinct processes passing 
in all directions through a coarse reticulum of fibres (VII 15). Both 
divisions of the fornix tract lose their distinct contours before the level 
of the anterior commissure is reached, the caudad tract, especially, 
fuses with the gray matter of the thalamus. The cephalad portion 
emerges immediately caudad to the commissure. Meynert’s . bundle 
at this level is some distance cephalad to the oculomotor tracts. 
Three more or less distinct masses of gray matter appear in the 
lateral aspect, the middle one being the largest and most densely nu- 
cleated and being recognized as the corpus geniculatum. 
The most remarkable nucleus remaining is the ganglion of the 
superior commissure or nucleus of the habenulas. This is a compact 
