iia 
THE CEREBRAL HEMISPHERES 789 
The fibers of the olfactory strie go to the piriform lobe and hippocampus, the trigonum 
olfactorium, the area parolfactoria, the subcallosal gyrus, and part of the gyrus fornicatus. The 
central connections of the olfactory apparatus are complex and are not yet fully understood. The 
anterior cerebral commissure contains fibers which pass from the olfactory bulb of one side by 
way of the medial striz to the bulb of the opposite side; also fibers which cross in it from the 
medial striz of one side to the piriform lobe of the opposite side. Many fibers pass to the 
hippocampus by way of the septum pellucidum, fornix, and fimbria. Other fibers pass in the 
column of the fornix to the mammillary body and thence to the thalamus by the thalamo-mam- 
millary bundle. 
The corpus callosum is the great transverse commissure which connects the 
two cerebral hemispheres through about half of their length. On median section 
— Olfactory bulb 
_--~ Cortex cerebri 
————Corpus medullare 
——- Caudate nucleus 
-Chorioid plexus 
~ Fornix 
; --Hippocampus 
Fic. 642—Brain or Horse, with LATERAL VENTRICLES OPENED BY REMOVAL OF UppEeR Part OF CEREBRAL 
HEMISPHERES AND Most OF THE Corpus CALLOSUM. 
(Fig. 639) it is seen to be arched from before backward, white in color, and com- 
posed substantially of transverse fibers. The middle part or truncus (Truncus 
corporis callosi) slopes downward and forward and is thinner than the ends. The 
anterior thickened end, the genu, bends ventrally and backward and thins out to 
form the rostrum; the latter is continuous with the lamina terminalis. The pos- 
terior end, the splenium, also thick, lies at a considerably higher level than the 
genu. The dorsal surface is convex in its length, concave transversely; it forms 
the floor of the longitudinal fissure. It is covered by a thin layer of gray matter 
(Induseum griseum), in which are strands of longitudinal fibers (Strie longitudi- 
nales); the latter are arranged in medial and lateral bundles (Stria medialis, strie 
