DEVELOPMENT OF THE HYPOPHYSIS 417 
4. The hypophysis of the adult 
A detailed description of the pup stage has been given (p. 400) 
as typical of the morphology of the adult condition (fig. 1). 
A drawing of a dissection of the hypophysis of an adult will 
show the position and relation of some of the parts more clearly 
(fig. 26). The anterior end extends almost to the optic chiasma, 
as noted by Sterzi and others. From a study of the models of 
the ‘pup’ stage and of sections of adults it appears that the 
middle part of the anterior lobe is more than a mere constriction 
separating a larger rostral from a smaller caudal part as Sterzi 
(09) described. In the pup this middle part is only a little 
shorter than either extremity, while in the adults it is much 
shorter. It is, however, distinctly marked. In some cases 
there are cystic outgrowths from the floor of this part; in others | 
the walls and floor are quite regular and therefore are distinctly 
different from either extremity. The middle part is smaller 
than either extremity in its dorso-ventral and lateral diameters 
in pups (figs. 24, 25) and in adults, but the changes in diameter 
from either end to the middle part in adults takes place gradually 
and the parts are not so definitely marked, except in those cases 
in which no glandular outgrowths occur from the middle region 
which is much more prominent in sections and in wax reconstruc- 
tions than is shown in dissections. The superior lobe projects 
some distance laterally on the ventral side of the vascular sac. 
It is difficult to make out the lateral limits of this part in the 
dissected specimen, as it seems to be continuous with the ventral 
surface of the vascular sac (fig. 26). In transverse sections, 
however, the lateral extent of the wings of the superior lobe is 
clear. "The superior lobe is convex dorsally and closely at- 
tached to the saccus vasculosus. The latter dips down on either 
side of the caudal end of the anterior lobe and so partially sepa- 
rates the lateral wings of the superior from the anterior lobe. 
The inferior lobes no longer resemble the sac-like structures 
with cystic outpouchings of the pup stage. Both superior and 
inferior walls have developed a mass of tubular-like glands. None 
of these was observed extending cranialward, as described by 
