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 earlv in the 



FIG. 130. View of the inner surface of the Right Half of 

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



flll tVlP nrinriml chert) F ' Frontal lobe; P ' P arietal ; O, occipital : T, tem- 



** poral ; I, olfactory bulb ; II, right optic nerve ; fp, calloso- 



of them are dlS- marginal fissure; p, perpendicular fissure; p', internal per- 



. , ,, pendicular fissure ; h, calcarine fissure ; g g, gyrus fornicatus ; 



tin CUV traceable. c C) C0 rpus callosum; s, septum lucidum; /, placed between 



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



upper part of the third ventricle, immediately below the 



manifest them- velum interpositum and fornix ; v', in the back part of the 

 col na -fivcf third ventricle below the pineal gland, and before the entrance 



11 to the 'aqueduct of Sylvius;' v", in the lower part of the 

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

 f A.I i a passing backwards from the tela choroidea ; p v, pons Varolii ; 



lace are the ns- Ce> cerebellum, 

 sure of Sylvius' 



and the ' fissure of Kolando.' 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 7 ) marking the anterior boundary 

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

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



