THE PINEAL BODY 221 



slender stalk made up almost exclusively of nerve fibers con- 

 nects this organ with the tip of the proximal portion and con- 

 stitutes a nervus pinealis, in the strict sense, which terminates in 

 the posterior commissure. Galeotti 140 in Spelerpes fuscus 

 observed evidence of secretory activity, and this he also found in 

 Bufo and Rana. The evidence of secretory activity depended 

 upon the appearance of fuchsinophile granules in the cytoplasm. 

 Studnicka, 391 following Galeotti, found, as he had previously 

 observed in selachians and teleosts, many cells in adult amphibia 

 containing cytoplasmic granules. These he interpreted as cells 

 having a sensory nature. Galeotti based his belief of secretory 

 activity in the pineal organ not merely upon the presence of 

 fuchsinophile granules, but quite as much upon epithelial char- 

 acters of the cells which were arranged in alveoli, thus giving 

 the end-vesicle and the proximal portion a glandular appearance. 



It is apparent from this evidence that amphibia in general 

 present a very abortive attempt toward the formation of retinal 

 and lenticular structures, while the end-vesicle and the proximal 

 portion of the pineal organ both show some evidence of glandu- 

 lar formation. 



Histological evidence in reptilia. The finer structure of the 

 epiphyseal complex in the primitive reptiles, including Spheno- 

 don and lacertilia, shows that in these forms the parapineal 

 organ attains its highest differentiation as a visual structure. 

 The pineal organ, however, shows no tendency whatsoever in 

 this direction, while, on the other hand, its proximal portion 

 affords many indications that its differentiation has been along 

 glandular lines. In ophidia and chelonia the proximal por- 

 tion of the pineal organ alone persists and has the appearance 

 of a highly vascular, richly branched, tubular gland. The 

 structure generally known as the pareital eye is a prominent 

 morphological feature in primitive forms of reptiles. It is 

 absent in certain geckonidae and in a number of agamidae. It 

 attains its greatest differentiation in Sphenodon and here pre- 

 sents a well marked retina, lens, vitreous, cornea, and nerve, the 

 latter relating to the ganglion habenulae. The accessory struc- 

 tures related to the parietal eye, including the cornea, parietal 



