INHERITANCE OF MENTAL DEFECTS AND DISEASE 29 



INHERITANCE OF FEEBLE-MINDEDNESS 



Feeble-mindedness may occur in various degrees from the 

 lowest grades of idiocy to the condition occurring in those who 

 are classed as "dull normal." In most of the feeble-minded there 

 is a general lack of mental power, but exceptional cases occur in 

 which highly developed special talents go along with marked 

 deficiency in other respects. Blind Tom who possessed a phenom- 

 enal aptitude for playing any piece of music he may have heard 

 was practically an imbecile. Often these " idiots savants " possess 

 remarkable memory, as in the case of the boy described by Lang- 

 don Down, who could repeat verbatim pages from a book that he 

 had once read. Some of the mathematical prodigies are otherwise 

 mentally defective. Heron reports a boy, nearly an idiot, who 

 when given a man's age could calculate quickly the number of 

 minutes he had lived. Another boy could multiply any three 

 figures with any three others almost as rapidly as they were 

 written, although he was of a very low grade of mentality. 



From a eugenic standpoint the very lowest types of mental 

 defectives, such as idiots, do not present a very difficult problem 

 as they cannot care for themselves and are, therefore, usually 

 kept as institutional charges where they cannot propagate their 

 kind. Similarly the low grades of the feeble-minded are quite 

 easily dealt with, so that there is a tendency for the very lowest 

 types of mentality to disappear of themselves. The death rate of 

 the lower grades of defectives is relatively high. Barr states that 

 out of 625 mental defectives the largest number of deaths oc- 

 curred between the tenth and twentieth years; "comparatively 

 few passed the twenty-fifth year." Tuberculosis, epilepsy, 

 pneumonia and diseases of the digestive system were the most 

 frequent causes of death. Institutional life may have increased 

 this death rate, as it only too often has done in homes for orphan 

 children, but the lower grades of mental defect belong to poor 

 physical stock which has a natural tendency to become extinct. 

 It is the higher grades of feeble-mindedness which are eugenically 

 and socially the greatest menace. Apparently normal and even 



