Sorensen, Study of Epiphysis and Roof of Die?icephalon. 57 



several cells which were considerably pyriform-inflated were 

 found large colorless vacuoles. These vacuoles appeared to con- 

 tain a hyaline mass which, excreted from the cells, attaches 

 itself to the latter, assuming the form of little bodies. Upon 

 closer examination some little bodies were found separated 

 from the cells, others divided in several parts, and several per- 

 fectly free. In the case where the entire cavity was filled they 

 undoubtedly had this origin. In the pigmented retina some- 

 times the pigment bodies penetrate in a larger or smaller quan- 

 tity into these hyaline prolongations. The hyaline filaments 

 sometimes leaving or starting from these little bodies are un- 

 doubtedly coagulum. The vitreous bodies have very little color 

 in the preparations strongly colored with picro-carmine or eosin. 

 They may be a pale rose color. They were found in prepara- 

 tions made in chromic acid, nitric acid and dilute Muller's fluid. 

 Perhaps they serve to refract the light. The entire organ has 

 no lens. These little bodies probably serve to supply the lack 

 of a lens. 



2. Parapineal Organ. The parapineal organ is always 

 much less developed than the pineal organ but much more dif- 

 ferentiated than Beard has found it. The superior wall is slight 

 and composed of a single layer of cells. The inferior wall, the 

 retina, is thicker, and is attached by its own center below to the 

 separated anterior portion of the left habenular ganglion (zirbel- 

 polster). The elements of the retina can be distinguished with 

 difficulty. In some sections rod-like cells have been found, dis- 

 tinct in contour, strongly stained, and analogous to the rods of 

 the retina of the pineal organ. Among the latter are found 

 numerous nuclei disposed in several rows, belonging to smaller 

 cells with various forms. Above the latter is a nervous layer 

 united to the ganglion nerve fascicles. No union of the rods 

 with the nerve was noticed. 



3. Central innervation of the parietal organ. The nerve 

 filaments have been followed after their entrance into the brain 

 and even within the brain. They were lost sight of in the post- 

 commissure. It is not decided whether the filaments traverse 

 this commissure in entering the posterior part of the brain, or 



