Charles Sedgwick Minot 



87 



cliyma, as can be seen iu Fig. 11. Comparison with Fig. 5 shows that 

 the velum has elongated, but comparatively much less than the epi- 

 physis. Both commissures have grown, causing each a local thickening 

 of the brain-wall. Our notions of the structure may be completed by 

 the examination of cross sections, compare below Figs. 11 and 12. 



In embryos of 34.0 mm. we find that there has been an obvious growth 

 of all the parts, and in addition we note: — 1, that the paraphysal arch 

 is more accentuated, and has changed in form so that it has now be- 



Fiq.] 



Fig. 7. Embrj'o of 34.0 mm. Sagittal series, 363, section 173. 

 Fig. 8. Embryo of 40.5 mm. Sagittal series, 370, section 169. 



gun to bend upwards, so as to reach above the level of the fore-brain 

 in front of it; 2, the ependyma on the anterior side of the velum has 

 thinned out, so that it is about the same as the ependyma upon the 

 posterior side; 3, the epiphysis, Ep., is clearly differentiated into a ter- 

 minal enlargement and a narrower stalk. 



In an embryo of 40 mm., Fig. 8, we may point out the general 

 growth, which has continued in all the parts, and besides must direct 

 attention to the following special points: — the marked thickening of 

 the nervous portion of the fore-brain wall, the upward protuberance 

 of the paraphysal arch; the decided curvature of the velum, and its 



