SELF-PRESERVATION AND THE MENTAL LIFE 141 



and function there is instructive material in those 

 regressive changes which develop in the brains of 

 persons who have been previously without noticeable 

 mental abnormalities. In such persons the demon- 

 strable alterations in structure may be either localized 

 or diffuse, and the nature of the resulting functional 

 defects is correspondingly stamped. The diffuse le- 

 sions are common causes of disorders of personality, 

 in which a general memory defect and general mental 

 failure or dementia are prominent. There are two 

 diseases in which such disorders of personality are 

 very striking general paralysis of the insane and 

 senile dementia. Both are diseases in which the 

 cortex or rind shows a progressive decay. The 

 highest faculties of mind and personality have their 

 physical seat in the cortex of the brain, and with its 

 slow disintegration there is a pitiful deterioration of 

 judgment and character with loss of memory, 

 tremor and defects in speech and writing. In both 

 these diseases there is a fair correspondence between 

 the mental loss and the physical alterations of the 

 brain. There are, in fact, no better examples of the 

 dependence of personality on the integrity of quite 

 definite physical structures. 



Where there are localized defects of the cerebrum 

 we get a different order of brain disturbances, in 

 which there is no actual mental disorder in the ordi- 

 nary sense, unless, indeed, there are implicated those 

 parts which subserve certain very special kinds of 

 mental activity, as, for example, the organs of speech 



