THE GENERAL FUNCTION OF THE CEREBRUM 



665 



to assume a more diversified position in nature. This is true partic- 

 ularly of birds, their more elaborate powers being directly attributable 

 to a greater development of the corpus striatum and cerebellum. In 

 mammals, on the other hand, these bodies remain relatively small, 

 whereas the external shell of the cerebrum, or pallium, is brought into 

 much greater prominence. These differences have led to the division 

 of the contituents of the cerebrum into two groups, namely, those 

 which are intimately associated with the sense of smell, and those 

 which are chiefly concerned with vision, hearing and touch. The 



Body of corpus calloaum 

 Intermediate mass 

 Fornix 

 Septum pellucidum 



MargiruU 

 Genu of co^-piu cailomm 

 CHngulate 



Tela choroidea ventriculi tertii 

 Cingulate gyrus 

 Callosal fissure 



Splenium of corpus callosum 

 Paracentral lobule 

 Central fissure 



Suhparietal fissure 

 Precuneate lobule 

 Parieto-occip. fissure 

 Calcarine fissure 



Cuneate lobuU 



Lamina terminalis 



Optic recess 



Optic nerve 



Optic commissure 



Hypophysis 



Corpus mamillarei 

 Zrd ventricle 

 Cerebral peduncle 

 Pons 

 Suprapineal recess 

 Pineal body 

 Cerebral aqueduct 



Cerebellum 

 Medulla oblongaia 

 4th ventricle 

 ' Superior medullary telum 

 Corpora quadrigemina 



Fig. 336. — Median Section of an Adult Brain. (/. Symington.) 



former are spoken of collectively as the archipallium, and the latter as 

 the neopallium. The first system is the more primitive. Its impor- 

 tance gradually diminishes in favor of the second. 



As a natural consequence of this evolution we find that the cerebral 

 hemispheres increase in volume and complexity until, in the mammals, 

 they become larger than the whole of the rest of the brain put together. 

 They overshadow the primitive olfactory apparatus completely, and 

 extend backward across the brain-stem as far as the middle of the 

 cerebellum. In this way, it comes to pass that the primitive reflex 

 cerebrum of the lower forms which is largely apportioned to smell, 



