; i;i;i>i.i;icK TILNKV \xi> LTTHKR F. WAKKKX 



in which there were several layers of cells, including rod- and 

 cylindrical-shaped cells measuring from 7.4 to 8.3 micra in 

 diameter. There" were also some larger cells scattered among 

 the rod cells with a mean diameter of 14 micra. He found in 

 the ret ina many nerve fibers which made their way into a definite 

 fasciculus constituting a parapineal nerve. Studnicka 388 did 

 not agree wholly with Owsiannikow in the idea that the para- 

 pineal end-vesicle was as well developed as the corresponding 

 structure of the pineal organ. He states that the difference 

 between these two structures is the fact that the parapineal 



Pe<l 



Ha 



Pp Pf 



Fig. 4$ Sagittal section of the pineal and parapineul organs in Aminoccctes 

 with silver impregnation, according to lU't/ius, 1895. 



Ls., lamina terminalis; I'f., paraphysis; /'/*., parapineal organ; Ifn., habenular 

 ganglion; l\'</., ret inn; /'///., pellucida; \./>/n., pineal nerve. 



end-vesicle is not as highly developed a retinal structure as is 

 the case with the pineal end-vesicle. Studnicka, however, finds 

 that there is in the dorsal wall of the parapineal vesicle a definite 

 pellucida made up of several layers of cells. Those cells iden- 

 tified in the retinal layer by Owsiannikow 295 and Studnicka 388 

 aa the rod cells were recognized by Retzius 1 " in 1895 by means 

 of the ( lolgi method as bipolar cells. 



By this method l!et/iiis : ' :il " was able to trace nerve fibers which 

 took origin in the left li;ibenul;ir ganglion and passed to the 

 p.'ir.-ipiiieal end- vesicle. Leydig-" 1 '-' in l'<'lr>itni/.:-<m. fluviatilis 

 found that the parapinea.1 end-vesicle was less de\-eloj)e(l, but at 



