THE INHERITANCE OP SYNDACTYLISM 
17 
THE INHERITANCE OF SYNDACTYLISM. 
HENRY ALBERT. 
(ABSTRACT.) 
An instance of thirteen cases of syndactylism (or fused or 
webbed fingers or toes), traced through four generations was 
reported. The element of heredity is obviously apparent. In 
view of the recent report of a family with cases of syndac- 
tylism in which the inheritance of the abnormal union of the 
digits apparently conformed to Mendel’s law, as a dominant 
character, an effort was made to determine if the Mendelian 
law also applied to the cases in question. It was determined 
that although the disease was due to a factor which was ap- 
parently dominant rather than recessive it did not conform en- 
tirely to Mendel’s law. That it is not due to a Mendelian re- 
cessive character is shown by the fact that in three instances 
the disease appeared in children, neither of whose parents were 
affected by it and in each instance the family history of at 
least one of the parents was negative for the disease in ques- 
tion. To have a disease due to a recessive character appear 
in an individual, neither of whose parents are affected by it, 
we must assume that both parents are hybrids as regards the 
condition in question. 
Nor does it entirely conform to a Mendelian dominant char- 
acter, since if it did, we would expect that if the disease ap- 
peared in the offspring it should be present in at least one 
of the parents. 
It is probable that the explanation for the lack of con- 
formity of our cases to Mendel’s law is due to an inhibition 
of the activity of the determiner for the disease in question 
by some other factor, causing the disease in such cases to be 
latent. The absence or non-operation of such inhibiting factor 
may again cause the disease to appear. 
Department op Pathology and Bacteriology, 
State University op Iowa. 
