48 HEREDITY IN RELATION TO EUGENICS 



uniform for the people of a certain social class such as the 

 members of one and the same family belong to ; so it is not 

 strange that some famihes with perfect structure and high 

 resistance should be long lived (Fig. 18) and others, with 

 organic defects and low resistance, should be short Uved 



UtO ...DtQ 



app«diJ^uLi£? }£^2Sk 



t47nTO 



teart-valves| tube 



cb d) 6 S 6 6 



t72 



heart disease 



t42 LJy ^t44 



clsfective heart-valv es | tu berctilosU 



tSyrs 



Fig. 19. — Fragment of pedigree of a high class family with slight longevity- 

 due in part to heart defects and non-resistance to tuberculosis. The latest 

 gen^ation comprises only young children. F, R.; Pyn. 1. 



(Fig. 19). Thus, while longevity is not a biological unit of 

 inheritance a person belonging to a long lived family is a 

 better ^^risk" for' a life insurance company than a person 

 belonging to a short lived family. 



7, Musical Ability 



This quality is one that develops so early in the most 

 marked cases that its innateness cannot be questioned. A 

 Bach, matured at 22; a Beethoven, pubUshing his composi- 

 tions at 13 and a Mendelssohn at 15; a Mozart, composing 

 at 5 years, are the product of a peculiar protoplasm of whose 

 tenacious qualities we get some notion when we learn that 

 the Bach family comprised 20 eminent musicians and two 

 score others less eminent. The exact method of inheritance 

 of musical ability has not been sufficiently analyzed. Hurst 

 (1908) suggests that it behaves as a recessive, as though it 

 depended on the absence of something. The '' Family 

 Records^' afford some data on this subject. A statement of 

 the grade of musical ability of each person, whether poor, 



