THE PINEAL BODY 



37 



bellum. This region contains in more or less rudimentary form 

 the following structures: A paraphysis, a very simple velum 

 transversum, a small and compressed dorsal sac, a commissura 

 habenularis, an epiphysis, undoubtedly the homologue of the 

 proximal portion of the pineal organ with a definite pineal recess 

 and a pineal peduncle, a pars intercalaris posterior of varying 

 size depending upon the species, and a fairly well-marked pos- 

 terior commissure. The relation of the epiphysis to the brain 

 roof in birds is different from that encountered in any of the 



Kl 



IS 



^ W . 



Ch Cp ; 

 M 



Fig. 7 Schematization of the pineal region in Aves, according to Studnicka, 

 1905. 



Ls., lamina terminalis; Pf., paraphysis; Ds., dorsal sac; Ch., commissura 

 habenularis ; Ep., proximal portion of pineal organ (epiphysis); Cp., posterior 

 commissure; M., midbrain. 



lower forms in that here the axis of the organ is at right angles 

 to the roof, whereas, lower in the scale the tendency has been 

 for the body to show a definite anterior or ventral flexion. 



9. The pineal region in mammals 



This region is made up as follows in the mammal : Following a 

 thin lamina supraneuroporica there occurs, according to Fran- 

 cotte 129 in 1894 in the early stages of development in the human 

 embryo, a short tubular process which he terms the paraphysis. 



