THE HYPOPHYSIS IN REPTILES 215 



is Seessel's pouch, and between the two a third and smaller 

 pouch, similar to one described by Valenti in Lacerta. The 

 latter disappears, but it could not be ascertained whether it is 

 included in the hypophyseal anlage. Rathke's pouch soon dif- 

 ferentiates into a median and two lateral lobes. In 5 mm. 

 embryos the anterior lobe is formed by the evagination of the 

 epithelium, cranial to Rathke's pouch. The stalk is solid and 

 numerous buds have appeared on the body in 10 mm. embryos. 

 Except in the median lobe and in an anterior prolongation of 

 the median lobe, the lumen disappears, and the lateral lobes 

 become enclosed in the cerebral coverings, losing their connec- 

 tion with the hypophysis. Bruni has given some interesting 

 figures illustrating the change in position of the hypophyseal 

 stalk. The stalk first extends forward, then caudalward, and in 

 older embryos, again cranial ward. 



Another recent article on the development of the hypophysis 

 is by Woerdemann ('14), who believed that there is a single 

 hypophyseal anlage, and accepted this as the view of recent 

 investigators. From this single thickened epithelium, Rathke's 

 pouch develops. Two lateral buds appear and still later an 

 anterior bud. The latter is a primary portion of the hypophysis, 

 though it appears late. All these parts are present in a 3 mm. 

 Chrysemys picta. Woerdemann considers the lateral buds inde- 

 pendent of Rathke's pouch (Gaupp's 'Mittelknospe') since the 

 latter opens by a somewhat constricted lumen into a main cavity 

 into which the lateral buds open separately. This cavity ('Mit- 

 telraum') is a part of the anterior end of the hypophysis and the 

 anterior lobe opens into its cranial end. The hypophyseal stalk 

 is attached to the ventral wall. 



In a 5 mm. embryo, Rathke's pouch is closely applied to the 

 infundibulum and is connected by a narrow neck to the anterior 

 end of the hypophysis. The lateral lobes grow dorsal ward, 

 under or into the cranial membranes, and become divided into 

 cell groups. The anterior lobe develops cell columns very early. 

 The hypophyseal stalk disappears and from the 'Mittelraum' 

 a solid bud develops, to which the lateral buds are attached in 

 9 mm. embryos. 



