MENTAL CHARACTERS IX MAX 149 



of his eight children, a girl of four and a half years, had 

 exactly the same trick. Darwin states that imitation 

 was out of the question. 



Considering now the inheritance of various forms 

 of mentality, Galton (1869), in his classical work, 

 Hereditary Genius, first dealt with the inheritance of 

 mathematical and various other forms of ability. 

 This and the subsequent studies are too well known 

 to require treatment here. Hurst first pointed out the 

 probabilit}^ that musical ability was a Mendelian 

 recessive. The same is apparently true of feeble- 

 mindedness, at least in its extreme form, two feeble- 

 minded parents almost invariably having only feeble- 

 minded children. The exceptions to the rule are 

 probably explainable by illegitimacy. The literature 

 of feeblemindedness is too well known and too 

 extensive for full discussion, but reference may be 

 made to some of the results. For the Mendelian 

 interpretation Goddart (191 2, 1914) and Estabrook 

 (191 6) may be cited. 



Goddart (191 4) finds that at least 50 per cent, of 

 the paupers cared for in American institutions are 

 feebleminded, and at least 50 per cent, of the pros- 

 titutes are estimated to be in the same condition. 

 Many criminals come in the same class, and there is 

 also a close relation between feeblemindedness and 

 alcoholism. On the basis of graded mental tests of 

 the Binet-Simon Measuring Scale of Intelligence, in- 

 dividuals are classed as idiots when their mental age 

 is 1-2 3^ears, imbecile when it is 3-7 3'ears, and morons 

 when it is 8-12 years. The latter would be called 

 feebleminded in England. The mental development 

 may stop at any age, and feeblemindedness is 

 essentially a condition of early suspension of mental 

 development. Various accidents and certain diseases 

 in childhood may result in feeblemindedness, but 

 it would appear that the great majorit}- of cases 



