94 



PERCIVAL BAILEY 



shaped, the anterior end being very broad. Heuser ('13) has 

 noted a similar condition in the pig. The commissura superior 

 is well marked (fig. 20, com. s.). 



It will be seen that the roof of the epiphyseal evagination 

 (fig. 20, e.e.) becomes epithelial for a short space in its uppermost 

 portion. Just in front of this epithelial region there is a small 

 aggre^'ation of cells (fig. 4, e.v.) which recalls the ball of cells 

 described in the epiphysis of the 19 mm. embryo. The nuclei 



Fig. 9 Section through the diencephalon of the 28 mm. embryo, H 91. X 

 6§. Slide 15, Sect. 228. 



Fig. 10 Section through the epiphysis of the 19 mm. embryo, H 173. X 150. 

 Slide 12, Sect. 4. 



of these cells stain densely like the nuclei of the ependymal 

 cells, and lie very close together. The cytoplasm is stained a 

 deep yellow like the cytoplasm of the ependymal cells. They 

 are surrounded by more Hghtly staining cells, and are nowhere 

 in connection with the ependymal cells. The lateral wail of the 

 epiphyseal evagination is very massive (fig. 4, e.r.). A ridge 

 arises from the postero-superior portion of the lateral wall of 

 the diencephalon and extends upward and backward to the 

 epiphyseal evagination (fig. 21, e.r.). 



