382 



PHYSIOLOGY 



CHAP. 



C.q. 



olf 



\ 



Fio. 199. Sagittal section of the brain of a 2^ months' foetus. (His.) 5 diameters. Abovi'. in I lie 

 right, the medial surface of the left cerebral hemisphere ; the wide cavity of the third ventricle 

 is limited above and in front by a thin lamina ; below, the iiifuiidibulnm and pituitary body. 

 The thalamus occupies the lateral and upper part of the cavity ; in front and below is the 

 foramen of Monro ; behind the thalamus another depression which opens into the slit of the 

 external geniculate body ; ulf, olfactory lobe ; ?>, pituitary body ; c.q., corpus quadrigeminum ; 

 cli, cerebellum ; m.o., medulla oblongata. 



Pio. 200. Right half of the brain divide<l by a vertical antero-posterior section (from various sources 

 and from nature). (Allen Thomson.) . 1, -2, 3, 3n., 36 are placed on convolutions of the 

 cerebrum ; 4, the fifth ventricle, and above it the divided corpus callosum ; 5, the third 

 ventricle; 5', pituitary budy; il, corpora quadrigemina and pineal sland ; +, the fourth 

 ventricle; 7, pons Varolii ; 8. medulla oblon^ata ; :', ceiebellum; I, the oltaetory bullj; II, 

 right optic nerve ; III, right 3rd nerve. 



