-the-wisp, may be puzzled to discover what purpose
could be attained by the stunted legs of Seth Wright's ram or the
hexadactyle members of Gratio Kelleia.

Varieties then arise we know not why; and it is more than probable that
the majority of varieties have arisen in this "spontaneous" manner,
though we are, of course, far from denying that they may be traced,
in some cases, to distinct external influences; which are assuredly
competent to alter the character of the tegumentary covering, to
change colour, to increase or diminish the size of muscles, to modify
constitution, and, among plants, to give rise to the metamorphosis of
stamens into petals, and so forth. But however they may have arisen,
what especially interests us at present is, to remark that, once in
existence, varieties obey the fundamental law of reproduction that like
tends to produce like; and their offspring exemplify it by tending
to exhibit the same deviation from the parental stock as themselves.
Indeed, there seems to be, in many instances, a pre-potent influence
about a newly-arisen variety which gives it what one may call an unfair
advantage over the normal descendants from the same stock. This is
strikingly exemplified by the case of Gratio Kelleia, who married a
woman with the ordinary pentadactyle extremities, and had by her
four children, Salvator, George, Andre, and Marie. Of these children
Salvator, the eldest boy, had six fingers and six toes, like his father;
the second and third, also boys, had five fingers and five toes,
like their mother, though the hands and feet of George were slightly
deformed. The last, a girl, had five fingers and five toes, but the
thumbs were slightly deformed. The variety thus reproduced itself purely
in the eldest, while the normal type reproduced itself purely in the
third, and almost purely in the second and last: so that it would seem,
at first, as if the normal type were more powerful than the variety.
But all these children grew up and intermarried with normal wives and
husband, and then, note what took place: Salvator had four children,
three of whom exhibited the hexadactyle members of their grandfather and
father, while the youngest had the pentadactyle limbs of the mother
and grandmother; so that here, notwithstanding a double pentadactyle
dilution of the blood, the hexadactyle variety had the best of it. The
same pre-potency of the variety was still more markedly exemplified in
the progeny of two of