82 



FREDERICK TILNEY AND LUTHER F. WARREN 



fibroid, hyaline substance attached to the free end of the cells in 

 the retina. This took on the form of a coagulum in the semifluid 

 contents of the atrium. Later Studnicka 888 in 1899 described in 

 Petronn/zon nuirinnx similar hyaline bodies and showed that they 

 were the thickened extremities of the retinal cells projecting into 

 the lumen of the end- vesicle. 





Fijr. 10 Sagittal section of the epiphyseal complex of IVtromy/on flaviatilis 



.showing syiicyt ial masses in 1 lie At num. according t o St udiiicka, IS'.!!). 



fill., pollucida; ]'<>.. ])iueal orjian; //</.. retina; /'/' parapineal organ. 



In this way these processes from the retinal cells formed a 

 virtual syncytium which almost completely fills the atrium. Of 

 the two walls forming the end-vesicle, the ventral wall presents 

 certain characteristics which seem to justify the recognition in 

 it of a retinal structure. Tor this reason the ventral wall is 

 known as the rrl./tui of the pineal origin in cyclost nines. The 

 dorsal wall has an entirely different structural character, and 

 because it is (jiiite without pigmental ion is known as the />< Ih/c/i/n. 



