THE PINEAL BODY 



105 



ent, has a form similar in character to the end-sac and is made 

 up, in the main, of small neuroglia cells. Nerve fibers constitut- 

 ing what has been called the pineal nerve of the stalk have been 

 observed making their way to the posterior commissure. Hill 180 

 observed in Salmo purpuratus, and Studnicka 386 in Cyprinus 

 carpio, Carassius auratus, Esox lucius, and Cobilis fossilis 

 what may be termed a tractus pinealis running from the pos- 

 terior commissure through the pars intercalaris posterior to the 



fy Cr Epid 



Ds Ch 



R 



Sch 



Fig. 55 The epiphyseal complex in Salmo purpuratus, according to Hill, 1894. 



V., velum transversum; Ds t , dorsal sac; Ch., commissura habenularis; R. 

 proximal portion; Po., pineal organ; Tp., tractus pinealis; Sch., pars intercalaris 

 posterior; Cp., posterior commissure. 



stalk and then in the dorsal wall of the stalk to the end-vesicle. 

 Hill says these fibers are connected with elements in the latter 

 vesicle. 



With reference to the site and relation of the pineal organ to 

 the skull, it has infrequently been observed that this organ 

 occupies a prefrontal fossa. What has been designated a 

 cornea, namely, a large mass of fiberless connective tissue above 

 the end-vesicle, has been described in teleosts, but there is no 

 parietal spot in any other form thus far investigated. 



