Sorensen, Study of Epiphysis and Roof of Dicnccphalon. 1 5 



His (j?5-'68) also took this view, but without personal 

 investigation. 



We find the short statement also by Foster and Balfour 

 (20-76, p. 90) that the pineal gland arises from the small 

 protuberance of the mid-brain on the third day of incubation. 



F. Schmidt (yp-62) states that the roof of the mid-brain 

 in the embryo of the ling is torn apart, excepting the poster- 

 ior part situated in front of the mesencephalon which persists, 

 and as a small bridge serves to unite the optic lobes. The 

 bridge, by a transverse fold, forms the limits of the mesenceph- 

 alon and bends posteriorly in the form of a cornet-like projection. 

 In six to seven months the tip of the projection becomes a pin- 

 eal gland. 



1 



Kolliker (./j-'6i, p. 240) corroborates the view that the pin- 

 eal arises from the posterior undivided part of the diencephalon, 

 and concludes with Tiedmann that the gland is first developed 

 in embryos of four months, while its stalk can be recognized at 

 three months. 



Reissner (75-51) indeed does not describe the pineal 

 gland, but figures and describes the processus pinealis quite cor- 

 rectly in the chick, and thinks that the projection has the same 

 relative position that the pineal has in the adult brain. 

 Reissner was the first to correctly interpret the processus pin- 

 ealis and described it as follows : In the first median vesicle 

 of the brain there arises in front a very short process, whose cav- 

 ity is joined to the cavity of the brain. Later it separates more 

 and more. The place where the process arises corresponds to 

 the place where the glandula conaria arises in the chick. 



Balfour (3-74) in Selachian embryos defined a small pro- 

 jection of the forebrain as the fundament of the pineal. 

 (Plate XV, Fig. 15). It is noteworthy, inasmuch as it shows 

 that the pineal is present in the oldest fishes and consequently 

 is an organ early developed. 



Group III. In this group of authors we find fuller discuss- 

 ions — Gotte on the toad (Unke), Lieberkiihn on the chick, and 

 Mihalcovics on birds and mammals. The developmental rela- 

 tions of the pineal according to Gotte {28-7$), are peculiar 



