SEPTUM, HIPPOCAMPUS, PALLIAL COMMISSURES 



449 



[Fig. 38 Opossum, parasagittal section through the fornix columns and pre- 

 commissural fibers. 1, hypothalamic fibers; 2, fibers coming from /the lateral 

 olfactory area; 3, fibers, part arising in and part passing through the olfactory 

 tubercle. Some of these go up to enter the association bundle of the hippo- 

 campus. This may receive fibers also from the medial olfactory tract (fig. 35). 



Fig. 39 Opossum, parasagittal section farther lateral than the last. The 

 section shows especially how the alveus after passing over the hippocampus and 

 subiculum runs on the ventricular surface of the general cortex and bends around 

 the angle of the ventricle to be distributed to the dorsal cortex. Compare figures 

 37 and 40. 



Fig. 40 Opossum (no. 11) section to show the degeneration of fibers following 

 a lesion in the dorsal cortex. In the small outline at the left the area of cortex 

 destroyed is shown by a black spot. This section is taken at the caudal end of 

 the lesion. Small bundles in the external capsule showing degeneration are 

 traced down to the amygdaloid region. The area outlined in the small figure 

 is the area destroyed in the second operation described in the text. 



