DEVELOPMENT OF MIND IN ANIMALS I3I 



highest type of mental activity, namely, a new covering of 

 the hemispheres called the neopaUium. This new covering, 

 which is proportionately so enormous in man, consists of a 

 surface of e^ray matter or neuron cell bodies, below which 

 is a layer of white matter, the connecting fibers of the cells. 

 The cerebrum with its new covering developed upward, 

 forward, and to the sides in an expansion that overshadowed 

 the rest of the brain. Even in the lowest mammals it is al- 

 ready large and important, and it becomes more and more 

 so through the primates to man. The neopallium complex 

 lies on the surface of the hemispheres, which become much 

 folded, giving temporal, frontal, parietal, and occipital re- 

 gions. x\dded to this device to increase surface area are the 

 convolutions, or infoldings, which become increasingly 

 complex as we reach the level of apes and man. In the mam- 

 mals an examination of these cerebral convolutions will give 

 a comparatively good indication of the intelligence of the 

 species. 



Since World War I the study of patients whose brains 

 have been injured by wounds or disease has produced a 

 large body of information on the localization of definite 

 human mental functions in various parts of the cerebral 

 hemispheres. Conscious motor activities seem to be in the 

 frontal part. There is a central groove, sulcus, which runs 

 across the top of the brain and down the outer side of each 

 hemisphere, in front of which are located areas definitely 

 associated with movement of specific portions of the body 

 from head to toes. Back of this groove are areas intimately 

 connected with the senses. From the skin and muscles, sense 

 impressions are led into a region just behind the central sul- 

 cus and just across from the motor areas of the frontal lobe. 

 At the posterior part of the hemispheres is an area devoted to 

 vision; speech reception is localized in the temporal areas, 

 close to the frontal region where speech is produced. An- 

 cient senses like taste and smell, once located in olfactory 

 lobes, are under the inner surface of the hemispheres. Stu- 



