CEREBRAL LOCALIZATION OF FUNCTION. 209 



of convolutions, and the exhibition of mental power. Throughout 

 the entire animal series, the increase in intelligence goes hand in 

 hand with an increase in the development of the brain. In man 

 there is an enormous increase in size over that of the highest 

 animals, the anthropoids. The most cultivated races of men have 

 the greatest cranial capacity ; that of the educated European being 

 about 116 cubic inches, that of the Australian being about 60 cubic 

 inches, a difference of 56 cubic inches. Men distinguished for 

 great mental power usually have large and well-developed brains ; 

 that of Cuvier weighed 64 ounces ; that of Abercrombie, 63 ounces ; 

 the average being about 48 to 50 ounces. Not only the size, but, 

 above all, the texture, of the brain must be taken into consideration. 



2. Pathology. Any severe injury or disease disorganizing the hemi- 

 spheres is at once attended by a disturbance or an entire sus- 

 pension of mental activity. A blow on the head, producing con- 

 cussion, or undue pressure from cerebral hemorrhage, destroys 

 consciousness ; physical and chemic alterations in the gray matter 



. have been shown to coexist with insanity, and "with loss of memory, 

 speech, etc. Congenital defects of organization from imperfect 

 development are usually accompanied by a corresponding deficiency 

 of intellectual power and of the higher instincts. Under these 

 circumstances no great advance in mental development can be 

 possible, and the intelligence remains of a low grade. In con- 

 genital idiocy not only is the brain of small size, but it is wanting 

 in proper chemic composition, phosphorus, a characteristic in- 

 gredient of the nervous tissue, being largely diminished in amount. 



3. Experimentation upon the lower animals e. g., the removal of the 

 cerebral hemispheres, is attended by results similar to those ob- 

 served in disease and injury. Removal of the cerebrum in 

 pigeons produces complete abolition of intelligence, and destroys 

 the capability of performing spontaneous movements. The pigeon 

 remains in a condition of profound stupor, which is not accompanied, 

 however, by a loss of sensation or of the power of producing 

 reflex or instinctive movements. The -pigeon can be temporarily 

 aroused by pinching the feet, loud noises, lights placed before the 

 eyes, etc., but soon relapses into a state of quietude, being unable 

 to remember impressions and connect them with any train of 

 ideas, the faculties of memory, reason, and judgment being com- 

 pletely abolished. 



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