420 



HISTOLOGY 



ing all the hind part of the brain. Their outer walls (constituting the 

 pallium, or mantle) become convoluted, forming gyri, with intervening 



FIG. 433. SAGITTAL SECTION OF THE BRAIN OF AN EMBRYO OF THREE MONTHS. (After His.) 

 bl.JCerebellum; hem., hemisphere; hy., hypophysis (posterior lobe) ; isth., isthmus; med., medulla oblon- 

 gata; mes., mesencephalon; ol. b., olfactory bulb; o. r., optic recess; p., pons; p. b., pineal body; p. s. 

 pars subthalamica; th., thalamus. 



o.b. 



cbl. 



FIG. 434- MEDIAN SAGITTAL SECTION OF AN ADULT BRAIN. 



cbl.. Cerebellum: c. c., corpus callosum; c. q., corpora quadrigemina; f., body of the fornix; hy., posterior 

 lobe of the hypophysis; med., medulla oblongata; o. b., olfactory bulb; o. r., optic recess; p., pons; 

 p. b., pineal body; p. 8., pars subthalamica; s. p., septum pellucidum; th., thalamus. 



sulci, and each hemisphere as a whole is divided into frontal, parietal, 

 occipital and temporal lobes, as described in works on gross anatomy. A 



