453 EVOLUTION, GENETICS, AND EUGENICS 



the Royal Society, one of them being Major Leonard Darwin, president 

 of the Second International Congress of Eugenics, from whose speech 

 we quoted a paragraph in the previous chapter. Darwin's aunt 

 married into the famous Galton family and her son was the late Sir 

 Francis Galton, the originator of the term "eugenics," whose work 

 we have just referred to. This is perhaps the greatest eugenic family 

 on record. 



The Bach family of musicians is another outstanding example of 

 the heredity of genius. The best-known member of the family is the 

 famous Johann Sebastian Bach. In six generations of Bachs there 

 were 47 musicians of note, 29 of whom ranked high in musical circles. 

 Johann Sebastian Bach was married twice and both times to a relative 

 bearing the name of Bach. His father married an aunt. There was 

 a great deal of rather close intermarriage in the family, which seems to 

 have helped to concentrate and preserve the high qualities of the stock. 



Most of the work done on the heredity of mental traits has been 

 expended on the study of defective and abnormal heredity, including 

 feeble-mindedness and the various so-called "insanities." 



The heredity .of Feeble-mindedness. — Feeble-mindedness, as de- 

 fined by Goddard, is "a state of mental defect existing from birth or 

 from an early age, and due to incomplete or abnormal development, 

 in consequence of which the person affected is incapable of performing 

 his duties as a member of society in the position of life to which he is 

 born." This is not a very exact definition, for, according to the state- 

 ment, a normal individual born into a community of geniuses might be 

 classed as feeble-minded. More specific are the following definitions 

 of various types of mental defectives. An idiot is one who, when adult, 

 has no greater capacity to learn than a child of two years or less. 

 An imbecile is one who rates mentally between two and seven years. 

 A moron is one who rates mentally from seven to twelve years. Usual- 

 ly the so-called "feeble-minded" individual is either an imbecile or a 

 moron, and much more often the latter than the former. Obviously, 

 then, there are many kinds and degrees of feeble-mindedness, and it 

 will often be difficult to draw the line between the high-grade moron 

 types and the lower levels of normal individuals. "This classifica- 

 tion," says East, "is arbitrary, but it serves a useful purpose when deal- 

 ing with feeble-mindedness as a social problem. Medically and geneti- 

 cally it means nothing — at present." If this is true, and we believe 

 it at least largely so, attempts to deal with feeble-mindedness as a 

 simple Mendelian recessive are likely to be only partially successful. 



