438 E£. A. BAUMGARTNER 
that the elongate-oval nuclei in this region in the younger embryos 
are changed into spherical ones. In the pup there are numerous 
columns extending dorsally, which consist of a central group of 
spherical, light-staining nuclei and a peripheral zone of cyto- 
plasm. Until some material between the 95 mm. embryos and 
the pup stage is studied, it must remain a question how these 
cell columns are formed. - It is possible that the cells with spheri- 
cal nuclei arrange themselves in groups and these groups then 
evaginate from the roof. The scarcity of these groups in the 
95 mm. embryos and in all late embryonic stages argues against 
such a possibility, although Sterzi’s observations on the presence 
of groups of spherical nuclei lying between masses of cells with 
oval nuclei should be taken into consideration. Numerous 
cyst-like outpouchings are present in some adults in the anterior 
part of the superior lobe, or, rather, between this and the roof 
of the caudal extremity of the anterior lobe. Some of these 
outpouchings show areas of cells similar to those forming the 
columns of the superior lobe, interspersed with areas of cells 
like those of the anterior lobe. The areas of cells resembling 
those of the superior lobe may form the entire wall or may lie 
on a basement of cells resembling those forming the anterior 
lobe which line the cavity. This would indicate that the regions 
of the anterior and superior lobes are not sharply separated, or, 
that the cells of this region which still resemble the embryonic 
condition change into cell columns of the superior lobe. This 
need not imply, however, that the cells of the anterior and infe- 
rior lobes are of a more embryonic type, although they may be 
more primitive phylogenetically. 
3. Development of the interhypophyseal canal 
The formation of the ridge connecting the inferior lobes on the 
dorsal (posterior) side of the hypophyseal anlage had been 
described. The character of the epithelium in this region in a 
21 mm. embryo, as stated above, differs from that of other parts. 
A ridge is prominent in a 34 mm. embryo. In a 40 mm. embryo 
the groove on the inside of this ridge is marked (fig. 8). Ina 
