PHYSICAL CHARACTERS IX :\rA\ 93 



Polydactyly and syndactyly (fingers or toes united 

 by a web of flesh) are also well known as inherited 

 conditions. Thus Reaumur's case of a Maltese couple 

 having a hexadactylous son, three of whose children 

 were again hexadactylous, is referred to by Huxley 

 {Darwiniana, p. 35). But usually such pedigrees are 

 incomplete, no account being taken of the normal 

 members of the family. Windle (1891) cites an 

 instance from Clement Lucas, where six fingers or 

 toes were inherited in a family through four genera- 

 tions. There appear to have been twenty-five 

 normals to seventeen hexadact^ds. In other records 

 the condition has been followed for six and five 

 generations respectively. There is some evidence that 

 Polydactyly is more common in negroes than in whites. 



Lewis (1909^?) describes Lucas's case, in which 

 in several related families in two generations there 

 are twenty-four normals to fifteen polydactyls. 

 Other records cited show that the abnormality may 

 skip a generation. There is a large degree of variation 

 in the extent to which this dominant character is 

 developed. Polydactylism is found not only in man, 

 horses, fowls, and guinea-pigs, but also in monkeys, 

 dogs, cats, and other animals. Bonavia (1895) gives 

 several pedigrees of hexadact3dy in man, with a good 

 many cases of the inheritance of various abnormalities 

 and sudden monstrous variations in a number of 

 different animals. 



Albert (191 5) describes a family with thirteen cases 

 of fused or webbed fingers or toes traced through finir 

 generations. The condition w^as obviously hereditary, 

 but was not inherited as a regular dominant or re- 

 cessive character. In three cases it appeared in 

 children neither of whose parents were affected, when 

 at least one of the parents had also a normal family 

 history. Probably such irregularities in the ex- 

 pression of a character result from inhibition of its 



