DEVELOPMENT OF THE HYPOPHYSIS 395 
stages (figs. 25 and 29). Later a bend in the medulla and a 
corresponding one in the parachordal plate changes the relation 
of the two cartilages. Also the forebrain has shifted from a 
position ventral to the medulla to a more dorsal and rostral 
. one (fig. 1). Sewertzoff showed the change in position of the 
hypophysis occurring with the change in position of the skull 
and brain (fig. 23). 
Rossi (’02) described the development of two lateral lobes in 
Torpedo. These, he stated, develop very early from the lateral 
walls of the evagination forming the hypophysis. He homolo- 
gized the different portions of the hypophysis as he found them 
with those described by Haller, but described two special lateral 
lobes which he stated have no homologous parts in Mustelus 
according to Haller’s description. 
Gentes (’06, ’07) found a close relationship between the vas- 
cular sac and the underlying hypophysis. In several short 
reports (’08) he described the lateral lobes and the development 
of the inferior lobes of the hypophysis. These two parts, he 
stated, form a ventral pituitary body. In a longer paper this 
author (’08) gave the results of his studies on the development 
and evolution of the hypophysis in Torpedo. He described 
two main parts, the superior and inferior sacs. The superior 
sac is further divided into posterior and anterior parts. The 
hypophysis begins as an outpouching which in 45 mm. embryos 
shows a beginning of its division into the two main sacs. From 
the posterior part of the superior sac many cords grow dorsal- 
ward, these later becoming tubular. Gentes homologized the 
superior lobe with the anterior lobe of mammals. The lateral 
lobes he believed persist through life. 
Ziegler (’08) ina series of figures of an embryo of Chlamydo- 
selachus, corresponding to Balfour’s Stage L—M, showed the 
hypophysis as an upward anterior-extending evagination from 
the mouth. The connection with the mouth is still a wide canal. 
Johnston (’09) described the hypophysis in Acanthias as con- 
sisting of a short anterior portion which grows toward the optic 
chiasma, and a longer posterior lobe directed toward the vascular 
sac. 
