SEPTUM, HIPPOCAMPUS, PALLIAL COMMISSURES 



441 



Figs. 25 to 30 Opossum, a series of transverse sections to show the relations 

 of structures in the medial wall of the hemisphere. The right half of each figure 

 is drawn from a series of cell-preparations, the left half from a Weigert series. 

 On the right side the cells of the hippocampal formation and adjacent structures 

 are drawn under the Edinger apparatus. The magnification (10 diam.) is too 

 low to allow the form or size of the individual cells to be represented in most 

 cases. The grouping is accurate. On the left side are drawn the fiber tracts of 

 the medial wall. 



Fig. 25 Opossum, transverse section through the olfactory peduncle. De- 

 scription in the text. 



Fig. 26 Opossum, transverse section just caudal to the olfactory peduncle. 

 For the destination of the medial olfactory tract, see figure 35. Note the mass 

 of large cells in the primordium hippocampi. 



Fig. 27 Opossum, transverse section through the rostral end of the caudate 

 nucleus and olfactory tubercle. The olfacto-cortical fibers arising from the 

 tuberculum curve around the rostral surface of the nucleus parolfactorius later- 

 alis, and appear to be interrupted in this section. Note the great extent of the 

 primordium hippocampi. 



