EVOLUTION OF MAN — SMITH. 559 



The ability to loarn by experience necessarily implies tlie develop- 

 ment, somewhere in the brain, of a something which can act not only 

 as a receptive organ for impressions of the senses and a means for 

 securing that their mfluence will find expression in modifying be- 

 havior, but also serve in a sense as a recordmg apparatus for storing 

 such impressions, so that they may be revived in memory at some 

 future time in association with other impressions received simul- 

 taneously, the state of consciousness they evoked, and tlie response 

 they called forth. 



Such an organ of associative memory is actually found m the brain 

 of mammals. It is the cortical area to which 11 years ago I applied 

 the term ''neopallium."* Into it pathways lead from all the sense 

 organs; and each of its territories, which receives a dofuiite kind of 

 impression, visual, acoustic, tactile, or any other, is linked by the 

 most intimate bonds with all the others. In spite of the disapproval 

 of the psychologists, we can indeed regard the neopallium as fulfillmg 

 all the conditions of the sensorium commune, which Aristotle and 

 many generations of philosophers have sought for 20 centuries; for it 

 is unquestionably a "unitary organ the physical processes of which 

 might be regarded as corresponding to the unity of consciousness." 

 (Wm. ]\IacDougall.) 



Nothmg that happens m this area m the course of its enormous 

 expansion and differentiation in the higher mammals materially affects 

 this fundamental purpose of the neopallium, which continues to 

 remain a unifymg organ that acts as a whole, though each part is 

 favorably placed to receive and transmit to the rest its special quota 

 to the sum total of what we may call the materials of conscious life. 



The consciousness which resides, so to speak, in this neopallium, 

 and is fed by the continual stream of sensory mipressions pouring 

 into it and awakening memories of past sensations, can express itself 

 directly in the behavior of the animal tlirough the intermediation of 

 a part of the neopallium itself,, the so-called motor area, which is 

 not only kept in intimate relation with the muscles, tendons, and 

 skin by sensory impressions, but controls the voluntary responses 

 of 1he muscles of the opposite side of the body. 



thp: differentiation of mammals and the effects of spe- 

 cialization. 



The possession of this higher type of brain enormously widened 

 the scope for the conscious and intelligent adaptation of the animal 

 to varying surrouncHngs, and in the exercise of this newly acquired 

 ability to learn from individual experience, and so appreciate the 

 possibiUties of fresh sources of food supply and new modes of hfe, 



' "The Natural Subdivision of the Cerebral Hemisphere," Journ. Anat. and Phys., vol. 36, 1901, p. 431 

 Arris and Gale lectures on the evolution of the brain, Lancet, Jan. 15, 1910, p. l.'iS. 



