ted through five generations; and in some cases,
after disappearing for one, two, or even three generations, have
reappeared through reversion. These facts are rendered, as Professor
Huxley has observed, more remarkable from its being known in most cases
that the affected person had not married one similarly affected. In
such cases the child of the fifth generation would have only 1-32nd
part of the blood of his first sedigitated ancestor. Other cases are
rendered remarkable by the affection gathering force, as Dr. Struthers
has shown, in each generation, though in each the affected person had
married one not affected; moreover such additional digits are often
amputated soon after birth, and can seldom have been strengthened by
use. Dr. Struthers gives the following instance: in the first
generation an additional digit appeared on one hand; in the second, on
both hands; in the third, three brothers had both hands, and one of the
brothers a foot affected; and in the fourth generation all four limbs
were affected. Yet we must not over-estimate the force of inheritance.
Dr. Struthers asserts that cases of non-inheritance and of the first
appearance of additional digits in unaffected families are much more
frequent than cases of inheritance. Many other deviations of structure,
of a nature almost as anomalous as supernumerary digits, such as
deficient phalanges, thickened joints, crooked fingers, &c., are in
like manner strongly inherited, and are equally subject to intermission
with reversion, though in such cases there is no reason to suppose that
both parents had been similarly affected.[29]

{14}

Additional digits have been observed in negroes as well as in other
races of man, and in several of the lower animals. Six toes have been
described on the hind feet of the newt (_Salamandra cristata_), and, as
it is said, of the frog. It deserves notice from what follows, that the
six-toed newt, though adult, had preserved some of its larval
characters; for part of the hyoidal apparatus, which is properly
absorbed during the act of metamorphosis, was retained. In the dog, six
toes on the hinder feet have been transmitted through three
generations; and I have heard of a race of six-toed cats. In several
breeds of the fowl the hinder toe is double, and is generally
transmitted truly, as is we