Fig. 26 Section a short distance in front of the last. It shows the rostral 
end of the lentiform nucleus and the spreading of the small-celled part of the 
pyriform lobe over the striatum as the superficial layer of the tuberculum. 
The whole width of pallium in figs. 25, 26 has the characters of the thickening. 
Fig. 27 Section through the rostral part of the tuberculum. The section 
passes just behind the peduncular constriction dorsally. Olfactory formation 
begins to appear 225 microns farther forward. The head of the caudate together 
with the deep or lateral parolfactory nucleus form one rounded mass covered 
externally by tuberculum. This is the nucleus olfactorius anterior of authors. 
Islands of Calleja are in the deep layer of the tuberculum. The tuberculum is 
continuous with the medial parolfactory nucleus and with the pyriform lobe. 
The pyriform lobe spreads medially in dorsal wall. General pallium is still pres- 
ent toward medial border and in some clusters of cells beneath pyriform lobe. 
Fig. 28 Section through the olfactory peduncle. Both sides are shown, the 
left side being sectioned near the rostral end of the oblique peduncle, the right 
side near the caudal end of the peduncle. Qn the right side fully developed 
olfactory formation appears in the roof; in the lateral wall the pyriform lobe; 
below, the end of the nucleus olfactorius anterior and the tuberculum. 
Fig. 29 Section through the caudal part of the olfactory bulb. Note the 
elliptical form of section on the right, the greater number of cells where olfactory 
glomeruli are present and the distribution of mitral cells with reference to the 
glomeruli. a, b, regions of this section which are drawn in figure 31. 
Fig. 30 Section through the anterior part of the right bulb. Note the tri- 
angular form of section and the fact that the dorsal root of the olfactory nerve is 
just entering the bulb. The bulb is nearly surrounded by glomeruli and the 
mitral cell layer is continuous except for a short space on the lateral surface where 
glomeruli are absent. 
447 
