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56 SpUt-Hcmd mid Split-Foot Deformities 
Summary and Chief Conclusions. 
1. A family containing 44 deformed members is placed on record. Of these 
17 are described in detail. 
2. Of the many varieties of split-hand and split-foot, one is most prominent 
and is of sufficiently common occurrence to merit the name " hereditary split-foot." 
A general account of it is given and reasons assigned for considering it a deformity 
sui generis. 
3. It usually affects the four extremities and shows great variability in all 
families in which it occurs. The types of deformity of the hands and feet are 
discussed and their relationship shown in different individuals and in separate 
families. 
4. All the cases of symmetrical split-foot, which have been found, have been 
included in the bibliography. Of these over 167 occur in families in which other 
members are similarly affected ; the remaining 13 are isolated. Nevertheless 
there is reason to believe that they are all of the same nature. 
5. The deformity consists mainly of an ectrodactyly, but is frequently associated 
with various grades of syndactyly and Polydactyly. 
6. The deformity has its origin in a " sport," which takes place in the parental 
germ cells or their precursors, probably in the latter. 
7. A plausible hypothesis is advanced in explanation of the quadruple nature 
of the sport and its tendency to recurring variation. It is supposed that the 
mutation originally occurs in that factor in the gametic cell (or its precursor) of 
the parent which governs the general and eventual conformation of the hands and 
feet, and that this mutation is transmitted as such. The succession of split-foot 
members in a family is consequently regarded as due to the transmission of a 
tendency to sport along definite lines. 
8. It is probable that nature's sports occur in definite directions. 
9. The transmission of " hereditary split-foot " does not follow the laws of 
Mendel. It is true that the deformity segregates, but it appears to a diminishing 
extent in succeeding generations. It shows no tendency to skip generations. 
10. It remains to be shown that this or any other human sport is permanently 
stable, or strictly follows Mendelian laws. 
BIBLIOGRAPHY. 
A. " Hereditary split-foot " families. 
1. Anders (E.). Jahrb. f. Kinderheilk. 1880-81, Bd. 16, S. 435. (3 cases.) 
2. Anderson (W.). B. M. J., June 12, 1886, p. 1107. (24 cases.) 
3. B^CHET. Essai, Paris, 1829 (cited by Hilaire, and Fort, loc. cit.). (5 cases.) 
4. BiDART. Eev. Mens, de I'Ecole d'Anth. de Paris, ann^e 2, p. 244 (cited by Windle, loc. cit.) 
(12 cases.) 
5. FoTHERBY (H. A.). B. M. J., 1886, May 22, p. 975. (17 cases.) 
6. Goldman (E. E.). Beitriige z. Idin. Cliir. 1891, Bd. 7, S. 249. (3 cases.) 
