T. Lewis and D. Embleton 
51 
The partial suppression of deformity in one generation has been referred to in 
dealing with atavism, but the latter, even if applicable as a term, offers no 
reasonable explanation of the phenomenon. It might be supposed that this partial 
"latency" could be brought about by the intervention of other characteristics 
which might themselves be transmitted*. As it is only in exceptional cases that the 
deformity of a parent is a gauge, and even then a by no means strictly accurate one, 
of the malformation which will appear in the offspring; and as at the same time 
the deformities in both parent and offspring, as in all members of a family, may be 
said to have been cast in the same mould, there is strong presumptive evidence 
that the inheritance depends on the transmission of some common factor. That 
representatives of the deformity are not transmitted in detail is obvious, for no 
two individuals have as yet been reported in any family in which the deformities 
were identical. Also in view of these multiple variations, it appears inconceivable 
that the originating factor is a recurring variation in the representatives of 
the hand or foot in the germ cells. It seems far more probable that a funda- 
mental factor, which influences the ultimate general conformation of the affected 
parts through their normal representatives, is at fault, that it is transmitted, 
and that its interaction with these representatives varies slightly in quality 
and quantity in different individuals and generations ; and that the varying 
interaction is produced by the interference of factors which may or may not be 
transmitted, such as those which may be conceived to account for the partial 
latency above mentioned. Such an hypothesis would not only offer a rational 
explanation of partial latency, but would render the quadruplieity of this and many 
other deformities less inexplicable ; at the same time accounting for the marked 
tendency to symmetry which usually exists. The hypothesis is in accord with the 
observations of Weismann on the subject of polydactylism (cp. Wilson and Windle 
also). Whatever view be taken it is difficult to avoid the conclusion that in spite 
of the variation in individual deformities, there is a common factor and fundamental 
scheme in transmission, both as far as hands and feet are concerned. 
Before passing to the inheritance of the deformity as a whole there remain two 
considerations ; the first in connection with sex preponderance, the second with 
twins. 
In Bedart's short family there was a predominance of the female sex in the 
proportion of 2 to 1, though taking deformed and undeformed together the male 
element was in the ascendant. In Mayer's report there is a male excess in the 
proportion 6 to 1 (Fig. 2). Apart from these examples sex plays no part in 
transmission, and therefore requires little comment. 
There have been in all four cases of twins. In two of these'- where the twins 
were heterologous, the female was in each unaffected. In a third instance 
(V, 33, 34), two children of opposite sex were normal. Lastly of Mayer's homo- 
logous twins (Fig. 2, III, 6, 7), arising from a deformed father, one only was 
deformed. Interest attaches itself to this ca.se in view of the opinion that certain 
* A phenomenon related to if not identical with the " cryptomerism " of Meudelians. 
7-2 
