14 Journal of Comparative Neurology. 



Tiedmann (89-16, p. 131) observed the gland in an 

 embryo of 4 months as a small flat body, whose stalks con- 

 nected with the optic lobes. During the next month the gland 

 developed, but remained flat and without brain sand. Tied- 

 mann did not study its structure. 



According to Serres (#2-' 24-' 28) the fundament of the 

 pineal is paired. Over the mouth of the aqueduct in the 3rd 

 month appear two small grey protuberances, which in the 4th 

 month grow from before backward, and form the pineal. The 

 gland has then anterior and posterior stalks ; the anterior aris- 

 ing from the optic lobes, the posterior from the post-com- 

 missure. 



According to Rathke (7J-39) the pineal arises from the 

 pia mater. 



Reichert ( 74-61 ) was well aware of the processus pinealis 

 in birds as described by Reissner, but he was unable to give any- 

 thing further concerning its significance. He thought it prob- 

 able therefore that the pineal was the outgrowth of the pia or 

 dura mater. 



Group II This group brought the development of the 

 gland into a closer relation with the roof of the 3rd ventricle 

 and some authors also recognized the processus pinealis. Here 

 belong v. Baer, Dollinger, F. J. Meckel, Remak, F. Schmidt, 

 Kolliker, Balfour, and His. 



V. Baer (^-'28) stated in his description of the roof of 

 the third ventricle in the case of birds, that the optic lobes are 

 united posteriorly by a delicate limiting membrane, which in 

 part becomes the posterior cephalic commissure, but anteriorly 

 is elevated and supplies the pineal. The pineal is therefore the 

 roof of the fore-brain evaginated and afterwards arrested, just 

 as the hypophysis is the degenerated point of the infundibulum. 



F. J. Meckel (50-' 15, Bd. I. p. 378) and Dollinger 

 (13- 14, p. 16) have shown a similar limiting membrane to be 

 the fundament of the pineal. 



Remak ( 7 <5 — ' 55) says only a little concerning the pineal. 

 A small protuberance arises on the roof of the mid-brain about 

 the 65th hour in the chick, which becomes the pineal gland. 



