THE PINEAL BODY 



69 



evidence of the epiphyseal complex in the chick makes its appear- 

 ance at five days and twenty hours as a sprout from the caudal 

 extremity of the interbrain roof-plate. This sprout contains a 

 narrow canal and at this very early period shows an apparent 

 differentiation into an expanded distal portion, a stalk, and an 

 expanded proximal portion. 



Fig. 36 Mesial view of forebrain reconstruction of chick of 5 days and 20 

 hours. X 100. The unshaded area shows the cut surfaces of the reconstruction, 

 according to Tilney, 1915. 



2, chiasmatic process; 4, chiasm; 7, epiphysis; 13, infundibular process; 20, 

 lamina terminalis; 25, mamrnillary region; 32, post-chiasmatic eminence; 33, post- 

 chiasmatic recess; 36, post-infundibular eminence; 38, pre-optic recess; 39, para- 

 physis; 41, supra-optic crest; 42, supra-optic recess; 44, telencephalon; 45, tuber- 

 culum postero-superius; 46, tubercle of the floor of Schulte. 



