THE INHERITANCE OF FAMILY TRAITS 170 



metacarpal bone only and the other two fingers are entirely 

 missing. This is, of com-se, a case of syndactylism, with 

 inheritance of a specific type. In a case cited by Marshall 

 (Trans. Soc. Stud. Disease in Children, III) in which for 



■ 



Fig. 163. — Fragment of a pedigree of a family showing hereditary club- 

 foot in 3 generations. So far as it goes this pedigree suggests that the 

 condition is due to a positive character. Drew, 1905. 



five generations this peculiarity appeared, each finger stopped 

 short at the proximal phalanx and the thumb was ill de- 

 veloped. Drew has recorded a case of club-foot in three 



i[0 



AiiiMMiiuuxiMiii 



Fig. 164. — Pedigree of a family of twins. Two twin brothers married. The 

 first had 10 children, all born as twins; 4 pair were daughters and 1 pair were 

 eons. Seven of the daughters are married and 4 have produced twins at 

 the first birth, nothing is known of the others. One of the sons is married 

 and has 3 single children. The second brother (first generation) had 8 

 children born as twins and 3 bom singly. Stocks, 1861. 



generations (Fig. 163). It is astonishing what a variety of 

 inheritable variations, that are often minute, are shown by 

 the hand and foot. The data are too limited to give assur- 

 ance as to the law of inheritance in each case. 



