14 ARTHUR DKNDY. 



of Histology^ (ed. vi). This bundle of fibres may easily be 

 traced from the uervous layer of the retina of the pineal eye, 

 in which it distinctly originates, to the surface of the brain 

 immediately behind the right liabenular ganglion and above 

 the posterior commissure. The latter part of its course, as 

 seen in a series of longitudinal sections, is shown in fig. 6. 

 Shortly before reaching the brain it divides into several short 

 branches. One of these {P.N. 1) is directly connected with 

 the epithelium of the ependymal groove in the manner already 

 described. Another, or perhaps several small bunches of 

 fibres {P.N. 2), comes off more posteriorly, and its fibres 

 probably pass into the posterior commissure {C.P.), and 

 apparently through this to the inner surface of the ependymal 

 groove {EiJ.G.). In all my sections, however, a small 

 shrinkage cavity (fig. 6, 8.C.) is developed just above the 

 posterior commissure, and the fibres of this branch of the 

 pineal nerve are probably thereby ruptured, so that they 

 appear to terminate abruptly above the shrinkage cavity, 

 while from the lower surface of this cavity very delicate 

 (nerve ?) fibres run obliquely across the posterior commissure 

 to the inner surface of the ependymal groove. Another branch 

 {P.N. 3) of the pineal nerve comes off more anteriorly than 

 either of those yet mentioned, and, curving forwards between 

 the right habenular ganglion and the ependymal epithelium, 

 joins the Meynert's bundle of the right side, and then, curving 

 upwards with the latter, forms a band of fibres which can 

 easily be traced into the middle of the habenular ganglion, 

 as shown in fig. 6. 



It thus appears that the pineal nerve is connected (1) with 

 the epithelium of the ependymal groove (both directly and 

 possibly also by fibres which pass through the posterior com- 

 missure), (2) with the right habenular ganglion, and (3) 

 with the i-ight bundle of Meynert. The connection with the 

 habenular ganglion was long since maintained by Gaskell 

 (4), but has since been doubted by Studnicka (2), who 

 maintains that, whereas the "parapineal organ" is connected 

 with the left habenular ganglion and the superior (haben- 



