Sorensen, Study of Epiphysis and Roof of Diencephalon. 2 1 



whole organ is very similar to lymphatic connective tissue, 

 although the development shows clearly that it is a fundament- 

 ally different structure. 



Relations of the pineal in man. From the position of the 

 pineal gland in the adult brain we can affirm with certainty 

 that the human pineal develops in a way similar to that of 

 mammals. The appearance of the pineal process in man occurs 

 so far as comparative conjecture can ascertain, about the 6th or 

 7th week. The peculiarity of the human pineal is that it pro- 

 jects caudally over the post-commissure which may be due to 

 the strongly developed callosal eminence. On this account also 

 the recessus infrapinealis takes a horizontal position and the en- 

 trance to this diverticle of the third ventricle is not below but 

 in front. Another peculiarity is observed in that the commissure 

 of the pineal stalk embraces the pineal posteriorly and afterwards 

 enters the epithelium of the tela choroidea media. At the 

 transition lies a rudimentary nervous ridge (Taenia rec. pin., 

 Reichert) similar to the taeniae medullares of the optic lobe. 

 Through the above mentioned bend of the fibrous membrane 

 there arises over the pineal, a second smaller diverticle of the 

 third ventricle, called the recessus suprapinealis. 



Stieda (86- 6g) in his article on birds and mammals says : 

 in birds the glandula pinealis grows in close proximity to the 

 pia mater, with which it is usually removed. The so-called 

 stalks of the glandula pinealis are so far as I have investigated 

 them nothing but blood vessels. In horizontal longitudinal sec- 

 tions which cut the glandula pinealis transversely, I find one or 

 two large blood vessels, cut transversely, in the mass of the 

 pineal. From the pia which invests the gland proceed connec- 

 tive tissue septa as well as blood vessels, into the substance. 

 Thus large and small reticular spaces are formed in which I see 

 a delicate anastomosed structure, cells, and imbedded lymphoid 

 bodies ; between them numerous capillary vessels. I have not 

 met with nervous elements. In mammals he found essentially 

 the same relations as in birds. 



In his "article on amphibians and reptiles, Stieda (86-75) 

 again refers to the pineal : on the roof of the diencephalon rests a 



