CEREBRUM. 495 



dependent on and associated with the anatomic integrity and the 

 physiologic activity of the cerebrum and its related sense-organs, the 

 eye, ear, nose, tongue, etc. 



From an examination of the anatomic development of the brain 

 in different classes of animals, in different men and races of men, 

 and from a study of the pathologic lesions and the results of ex- 

 perimental lesions of the brain, evidence has been obtained which 

 reveals in a striking manner the intimate connection of the cerebrum 

 and all phases of mental activity. 



1. Comparative anatomic investigations show that there is a general 



connection between the size of the brain, its texture, the depth 

 and number of convolutions, and the exhibition of mental power. 

 Throughout the entire animal series an 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 anthropoid apes. The most culti- 

 vated races of men have the greatest cranial capacity, that of the 

 educated European or American being approximately 92.1 cubic 

 inches (1835 c.c.); while that of the Australian is but 81.7 cubic 

 inches (1628 c.c.). Men distinguished for great mental power 

 usually have large and well developed brains; e.g., that of 

 Cuvier weighed 64.4 ounces (1830 grams); that of Abercrombie, 

 63 ounces (1786 grams). A large intelligence, however, is not 

 incompatible with a much smaller brain weight; thus, the 

 brain of Helmholtz weighed but 50.8 ounces (1440 grams); 

 that of Leidy, 49.9 ounces (1415 grams); that of Liebig, 47.7 

 ounces (1352 grams). The average arithmetic brain weight of 

 96 distinguished men was found to be 51.9 ounces (1473 

 grams) (Spitzka). 



2. Pathologic lesions and mechanic injuries which disorganize the 



cerebrum are at once followed by a disturbance or an entire 

 suspension of mental activity. Concussion of the brain or 

 sudden compression from a hemorrhage destroys consciousness. 

 Physical and chemic alterations of the gray matter of the cere- 

 brum have been shown to coexist with insanity, loss of memory, 

 of articulate speech, etc. Congenital defects of organization are 

 accompanied by a deficiency in mental capacity and the higher 

 instincts. Under such circumstances no great advance in brain 

 development is possible and the intelligence remains at a low 

 level. In congenital idiocy the brain is small, imperfectly 

 developed, and wanting in proper chemic composition. 



3. Experimental lesions of the brain in lower animals are attended 



by results similar to those observed in disease or after injury 

 in man. Removal of the cerebrum in the pigeon completely 

 abolishes intelligence and destroys the capability of performing 



