NATURAL SUBDIVISION OF THE CEREBRAL HEMISPHERE. 453 



progressive increase in size, whereas the other superficial parts 

 of the hemisphere become relatively or actually smaller, and 

 may even disappear almost entirely without any vital injury to 

 the individual {e.g., as in the anosmatic Cetacea). 



This neopallium is a great unlimited area (far removed from 

 the disturbing influences of the purely " administrative " parts 

 of the nervous system), where " impulses of diverse nature," 

 coming from all regions of the body and from all the sense 

 organs, " may meet and play upon each other." 



It is, in fact, that sensorimn comtiutne for which the ancient 

 philosophers sought in vain for so many ages, and which 

 Aristotle called at various times the irpoorou aio-Otjn'ipiov, as 

 well as the tjyeixoviKov {caput liumana: substantia:), the Kvpiov, 

 the eiriKp'ivov, and the apx*?' among many other names. These 

 ancient writers recognised that there must be somewhere in the 

 body some distinct organ where all the sensory impulses of the 

 body might meet and react one upon the rest, so as to produce 

 that consciousness of the various properties of one object which 

 everyone recognises. And many of these writers recognised 

 that this organ must at the same time be the "storehouse" of 

 impressions, and the dominant organ of the body, with the power 

 to quicken or restrain the activities of each and every part of 

 the whole organism in response, either directly or indirectly, to 

 the impressions from the outside world which are constantly 

 pouring into this common sensorium. 



Such an organ is the neopallium, and these special attributes 

 it does not equally share with any other cortical formation, or 

 any other part of the nervous system. 



It is therefore a region of the hemisphere which is in a greater 

 degree than any other part " tlie organ of the mind," and as 

 such is surely worthy of a distinctive name It might be called 

 the '' imrs crescens" [}iemisphcerii\ m reference to the peculiar 

 characteristic of its rapid expansion in the Mammalia ; and in 

 that case we might distinguish the rest of the hemisphere (ex- 

 clusive of the corpus striatum) as the " jJars limhica " [hemis- 

 'jplia:rii\, because its various parts are grouped around the hilum 

 of the hemisphere. 



But instead of selecting a new phrase, such as " jwns crescens" 

 I prefer to use the term neopallium, because the basis of this 



