Literary Notices. cxxv 



phatic vessel, since it does not possess the histological characteristics 

 of one. 



The last of the parietal nerve arises in the roof of the diencephalon, 

 between the origin of the epiphysis and the first fold of of the ple.xus 

 choroideus. It is there completely independent of the pineal gland. It 

 springs from a little mass of nervous cells. Its relations with the en- 

 cephalon, its fibrillary character and the absence of an endothelium prove 

 it to be a nervous structure. During all its course the nerve remains in- 

 dependent of the pineal gland. It is pale and translucent, permitting the 

 mesodermie layer to be seen below it. It is transitory and on the way to 

 atrophy. It is seen in the embryo but disappears in the adult, and 

 does not appear at all in very many specimens, 



" I cannot subscribe to the opinion of Francatte, when he holds that 

 there is a cellular cord in contact with the pineal eye in one hand and 

 the epiphysal body on the other, which represents the last trace of the 

 union between the individualized parts of the pineal, becoming the nerve 

 of the third eye. I hold that the parietal nerve is Completely independent 

 of the epiphysis. It receives no fibril springing from the epiphysal body. 

 In the embryo of the Anguis of 15 m.m. the epiphysis is very oblique 

 with reference to the parietal eye and rests against the posterior face of 

 the latter. The optic vesicle is a little distant from the diencephalon. 

 Its inferior face, opposite the encephalon, presents a little cellular mass. 

 This mass is the first indication I have observed of the future parietal 

 nerve. It is entirely independent of the epiphysis. 



" The results of my observations permit me to draw the following 

 conclusions : 



'' 1st. There exists in Anguis fragilis a parietal nerve which arises 

 from the arch of the diencephalon and ends in the pineal eye. It is not 

 a lymphatic vessel, for it is not tubular nor limited by an endothelium 

 and it has a fibrillary structure. 



" 2. This nerve is not derived from or dependent on the epiphysis, 

 but from its first appearance binds the pineal eye to the encephalon. 



"3. The nerve is transitory, making its first appearance in the em- 

 bryo of about 15 m.m. and disappearing at astage between 55 and 60m. m. 

 in length. 



" In Lacerta agilis the parietal eye does not proceed from an ulterior 

 differentiation of the distal extremity of the epiphysis, but the two or- 



