THE NERVOUS SYSTEM. 



505 



a portion of these two projections takes place, forming the commissura mollis 

 or massa intermedia. The condition at this stage is shown in Fig. 429. Later 



Ant. corp. quad. 



Diencephalon 



Tegmental 

 swelling 



Mammillary 

 body 



Tuber 

 cinereum 



Pallium 



Beginning of 

 fossa Syvii 



Ant ' "I olfact. 

 Post.j lobe 



Optic stalk 



Infundibulum Hypophyseal pouch. 



FIG. 427. Lateral view of the model of the brain of a 13.6 mm. human embryo (beginning of 6th 

 week). F, Beginning of frontal lobe; T, beginning of temporal lobe. His. 



this protrusion thrusts the lateral structures above described (the pulvinar, 

 geniculate bodies and brachia) to the side, the cavity of the lateral geniculate 



Eplthalnnius (Corpus pfneale) Mctathalamus (Corpora genlculata) 



Thalanuis 



Fissura 

 chorioidea 



Pallium 



Rhiuencephalon 



Corpus striatu 

 Sulcns hypothalainicus 



Hypothal 

 Chiasma 



Corpora quaclrigemina 



..Pedunculus cerebrJ 



FlG. 428. From a model of the brain of a 13.6 mm. human embryo, right half, 

 seen from the left side. His, Spalt'eholz, 



body being obliterated. The prominence itself extends to the tegmental swell- 

 ing (see Figs. 4 2 9-30) and there thus arises the possibility of direct connections 



