Chap. XIX.] 



DURING UTERINE LIFE. 



343 



whilst it increases both in thickness and in length. It 

 reaches back as far as the Optic Lobes, which are now 

 marked by a transverse furrow, and thus appear as true 

 * Corpora Quadrigemina.' The Occipital Lobes of the 

 brain become more developed. The general outline of the 

 Hemispheres 

 seen from above 

 is that of an 

 elongated oval. 

 During the 

 sixth month a 

 surprising devel- 

 opment of the 

 Fissures and 

 Convolutions 

 takes place, so 

 that early in the 



Fig. 130.— View of the inner surfuce of the Right Half of 

 seventh month the Foetal Brain of about Six Months. (Sharpey, after Rei- 



all the pidncipar^"|>/',/7^^^V"i^^L^' parietal ;0, occipital : Ttem- 



■•■ J- poral; I, olfactory bulb; II, right optic neive; /^j, calloso- 



of them are dis- marginal fissure; p, perpendicular fissure; ?/, internal per- 



. 1 , ^ -1 1 pendicular fisstire ; h, calcarine fissure ; gg, gyrus fornicatus ; 



tinCtlJtraCeaOie. ^ ^^ corpus callosum; s, septum lucidum; /, placed between 



Those which ^^^ middle commissure and the foramen of Monro ; v, in the 



vipper part of the third ventricle, immediately below the 



manliest them- velum Interposltum and fornix ; v', in ihe back part of the 



Qpl vp « fi r cjf nn *^^^^^ ventricle below the pineal gland, and before the entrance 



beiveh lllbl on ^^ ^^^^ 'aqueduct of Sylvius;' v", in the lower part of the 



the external SUr- third ventricle above the Infundibulum; r, processus pinealis 



i» 2.^ c It passing backwards from the tela choroidea; 2J 1-, pons Varolii ; 



lace are the tlS- ce, cerebellum. 



sure of Sylvius' 



and the ' fissure of Eolando.' The latter is scarcely distinct 

 till the end of the sixth month, but rather before this 

 period, according to Ecker, two other Fissures appear on 

 the inner aspect of the Hemispheres, viz., the 'internal 

 perpendicular ' (fig. 130, P^) marking the anterior boundary 

 of the Occipital Lobe and the ' calcarine fissure ' which it 

 meets below. The latter is generally regarded as a pos- 



