88 



On the Morphology of the Pineal Kegion 



peculiar insertion, which causes it to appear almost (in these sections) 

 like an appendage of the epiphysal stalk; the growth of the post-velar 

 arch between the base of the velum and the superior commissure, s. c; 

 and finally the well-marked thickening of the mesencephalic wall. 



I have examined also sagittal sections of the pineal region of em- 

 bryos of 50 and 60 mm., but, deeming it superfluous to present pictures 



Fig. 9. Embryo of 70 ram. Sagittal series, 431, section 293. x 30 diams. 



of them, will pass at once to Fig. 9, taken from an embryo of 70 mm. 

 The nervous tissue proper of the mid-brain and fore-brain has grown 

 very much so that these parts now form a striking contrast owing to 

 their increased thickness with the ependymal covering of the pineal 

 region, that is to say of the paraphysal arch, P, and velum, V, and the 

 epithelium of the epiphysis, which, however, is considerably thicker 

 than the velar and paraphysal epithelium. Around the superior com- 



