272 E. A. BAUMGARTNER 



to persist as isolated masses or to disappear; while in snakes they 

 completely disappear. The cortical zone or bands present in 

 turtles and alligators have not been described in other verte- 

 brates except in pig. 



The tip of Rathke's pouch gives rise to the pars infundibularis 

 (Tilney) or pars intermedia of the adult. The remainder of 

 Rathke's pouch and the early anterior bud give rise to the adult 

 anterior lobe, except for the thin cortex or band around it in 

 turtles and alligators. 



The three parts of the adult hypophysis are distinct onto- 

 genetically and histologically. 



The pars infundibularis or pars intermedia has a laminar ar- 

 rangement of columnar clear-staining cells. The parts derived 

 from the lateral buds are arranged in columns (or sometimes 

 acini) of clear-staining polyhedral cells. The anterior lobe 

 proper is formed of columns or acini, with clear-staining and 

 darkly-staining cells which may be acidophilic or basophilic. In 

 general, the pars intermedia and the parts derived from the 

 lateral buds may be considered the chromophobic and the an- 

 terior lobe the chromophilic part. 



ADDENDUM . 



P. L. Schroeder, working in my laboratory, studied the hy- 

 pophysis of ten newly-hatched Chrysemys marginata. In a 

 reconstruction of one of these he shows a persisting hypophyseal 

 stalk extending through the cortical band (derived from the 

 lateral lobes) and the cranium almost to the epithelium of the 

 roof of the mouth. In several specimens the anterior lobe is 

 short, the lateral lobes covering its anterior end. Considerable 

 variation exists in the length of the lateral lobes, especially the 

 pars tuberalis. A small lumen is present near the caudal end 

 of the anterior lobe of several specimens. 



