382 



CHAP. 



C,q. 



olf 



Fio. 199. Sagittal section of the brain of a 2 months' foetus. (His.) 5 diameters. Above, to the 

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

 is limited above arid in front by a thin lamina ; below, the infundibulum 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 ; olf, olfactory lobe ; p, pituitary body ; c.q., corpus quadrigeminum ; 

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



Fio. 200. Right half of the brain divided by a vertical antero-posterior section (from various sources 

 and from nature). (Allen Thomson.) J. 1, 2, 3, 3a, Sb are placed on convolutions of the 

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

 ventricle ; 5', pituitary body ; (5, corpora quadrigemina and pineal gland ; +, the fourth 

 ventricle ; 7, poris Varolii ; 8, medulla oblongata ; 9, cerebellum ; I, the olfactory bulb ; II, 

 right optic nerve ; III, right 3rd nerve. 



