242 



THE PINEAL ORGAN 



(1) There is a single median evagination, the tip of which being cut 

 off, forms the pineal eye, while the basal part retaining its connection 

 with the brain, forms the epiphysis, a pineal stalk, sometimes represented 

 by the pineal nerve, persisting between the two parts — Strahl (1884), 

 Lacerta ; Spencer (1886), Anolis ; Moloch horridus. 



-ect. 



Fig. 172, A, B, C. — Sagittal Sections through the Pineal Organ of Embryos 

 of Lacerta. (After Nowikoff.) 

 A : Lacerta vivipara, 3 mm. 

 B : Lacerta vivipara, 4 mm. 

 C : Lacerta muralis, 6 mm. 

 cutaneous ectoderm. pin. 



ect. 



I. : lens. 



p.e. : pineal eye. 



p.s. 

 ret. 



pineal nerve, 

 pineal stalk, 

 retina. 



(2) There are two separate and morphologically distinct evaginations, 

 situated in the median plane one behind the other, of which the anterior 

 gives rise to the parietal eye and the posterior to the epiphysis — Leydig 

 (1891) ; Studnicka (1893). 



(3) A single median evagination, which is subsequently divided into 

 two : (a) an anterior vesicle, the parietal eye, having an independent 



