T. Lewis and D. Embleton 
55 
the evidence points to the couclusion, despite the apparent segregation, that 
the transmission of hereditary spHt-foot is not governed by Mendelian laws. 
We have not yet seen a family tree of fair proportions which shows this adherence 
to Mendelism*. The family trees given by Bateson tend to show the same 
diminution in the proportion of affected to non-affected offspring in succeeding 
generations. In concluding this paragraph it may be said that evidence has not 
yet been produced which warrants the statement that any human sport is trans- 
mitted along the lines of Mendelism. 
Passing back to the original question, we find that the evidence of stability 
which Mendelism might have given is not forthcoming and that when the figures 
are taken on their own merit, they uphold the view expressed by Weismann that 
swamping of transmitted sports will eventually take place. As Weismann stated 
for Polydactyly, that no family deformity has been traced through six generations, 
so might the same statement be made for hereditary split-foot, but the statement 
of Weismann no longer holds goodf and there is no reason to disbelieve that the 
deformity of the " G " family will assert itself for several if not many more 
generations. 
Given the factor of inbreeding a split-foot race might quickly arise. In this 
connection the family quoted by Windle after Devay is of interest {Linnean Soc. 
Trans.), for it shows the development of a polydactylous race in an isolated village. 
Deformities may die out in one of several main ways. The deformity may be 
so gross as to render life impossible. Lesser grades of malformation though 
compatible with extrauterine life may predispose to early death, or handicap the 
individual in obtaining the necessaries of life. Other deformities, from their 
tendency to disfigure, may hinder mating. Others may render procreation 
impossible. Of these none, so far as can be seen, infiuence to any extent the 
prolificacy of individuals suffering from hereditary defects of the digits. In Devay 's 
family there appears, upon the introduction of new blood, to have been a gradual 
diminution in the severity of the individual lesions as they passed through 
succeeding generations. The same tendency was considered by Fotherby and 
Mayer to be present in their families, but the evidence in these last cases is 
inconclusive. The extermination of hereditary split-foot takes place by a pro- 
portionate decrease in the number of deformed offspring, arising from deformed 
parents, from one generation to the next. To what this diminution is due is a 
question to which at present no answer is forthcoming, but the fact as it stands is 
directly opposed to the supposition that human sports or their originating factors 
may be regarded as unit characters, transmitted along those definite lines which 
certain natural characters in animals have been shown to be inherited. 
* Though we have searched a large number. 
t Families of eight generations have been reported. 
