286 Frederick Tilney, 



ments entering into the formation of the hypophysis shows the follo- 

 wing: 



I. Pars Neuralis: 



1. Eminentia Saccularis. 



2. lufundibulum. 



3. Processus infimdibiili. 



II. Pars Buccalis sen Glandularis: 



1. Pars Juxta-neuralis, 



a) Pars tuberalis. 



b) Pars infundibularis. 



2. Pars Distalis. ^ 



The pars tuberalis represents the hitherto undescribed portion 

 of the hypophysis. 



2. In all of the species studied the several epithelial portions 

 may be differentiated not only by their topography but by certain 

 histological differences. These histological differences between the 

 pars tuberalis and pars infundibularis leave no room to doubt that 

 the juxta-neural portion of the gland consists of two distinct, mor- 

 phological elements. 



3. In addition to the histological differences between these two 

 parts, the ontogenesis of the organ as observed in the cat and common 

 fowl still further emphasizes the fact that the pars tuberalis and 

 pars infundibularis are morphologically distinct elements. The pars 

 infundibularis makes its appearance almost immediately after the 

 anläge of the buccal portion of the hypophysis is formed. The pars 

 tuberalis arises as a relatively late structure. It has its origin in 

 two secondary diverticula or sprouts from the body of the pituitary 

 sac. These sprouts, the tuberai processes, ultimately fuse with each 

 other across the median line, displace the body of the pituitary sac 

 ventrad and thus secondarily assume their juxta-neural position. 



4. The juxta-neural portion of the hypophysis is intimately con- 

 nected with the neural portion by means of nerve fibers, blood vessels 

 and connective tissue processes, so that the attempted separation of 

 these two portions could not fail to be accompanied by laceration or 

 destruction of the neural elements. 



