THE DEVELOPMENT OF THE BRAIN 15S 



these things, and these additions constitute what has 

 been named by Elliot Smith the Neopattium. Following 

 the same guide, we may therefore give comparatively 

 simple answers to our two original questions: (1) The 

 earliest Mammal inherited an archepallium capable of 

 great achievements; (2) the environmental possibilities- 

 of education will affect such a brain by increasing elabora- 

 tions of the neopallium, which the early Mammals started 

 to develop. 



How will arboreal life in particular influence this cere- 

 bral development ? For some aspects of this question 

 we can again turn to the paper by Professor Elliot Smith 

 to which we have already made reference, and the best 

 introduction may be made in the form of a quotation : 



" In the forerunners of the Mammalia the cerebral 

 hemisphere was predominantly olfactory in function; 

 and even when the true Mammal emerged, and all the 

 other senses received due representation in the neopallium, 

 the animal's behaviour was still influenced to a much 

 greater extent by smell impressions than by those of the 

 other senses. This was due not only to the fact that 

 the sense of smell had already installed its instruments 

 in, and taken possession of, the cerebral hemisphere, 

 long before the advent in this dominant part of the brain 

 of any adequate representation of the other senses, but 

 also, and chiefly, because to a small land-grubbing animal 

 the guidance of smell impressions, whether in search for 

 food or as a means of recognition of friends or enemies^ 

 was much more serviceable than all the other senses. 

 Thus the small creature's mental life was lived essentially 

 in an atmosphere of odours, and every object in the out- 

 side world was judged primarily and predominantly by 

 its smell: the sense of touch, vision, and hearing being 

 merely auxiliary to the compelling influence of smell. 



" Once such a creature left the solid earth and took to 

 an aquatic or an arboreal life all this was changed, for 

 away from the ground the guidance of the olfactory sense 



