From the foregoing survey of the available sources of information
concerning the origin and history of the race of dancing mice the
following important facts appear. There are four theories of the origin of
the race: (1) origin by selectional breeding (Haacke, Zoth, Milne-
Edwards); (2) origin through the inheritance of an acquired character
(Kishi); (3) origin by mutation, inheritance, and selectional breeding
(Saint Loup, Kammerer, Cyon); (4) origin by natural selection, and
inheritance, favored by selectional breeding (Landois). Everything
indicates that the race originated in China. It is fairly certain that
individuals with a tendency to move in circles appear at rare intervals in
races of common mice. It seems highly probable, in view of these facts,
that the Chinese took advantage of a deviation from the usual form of
behavior to develop by means of careful and patient selectional breeding a
race of mice which is remarkable for its dancing. Even if it should be
proved that the mutation as it appears among common mice is not inherited,
the view that slight deviations were taken advantage of by the breeders
would still be tenable. The dancing tendency is such in nature as to unfit
an individual for the usual conditions of mouse existence, hence, in all
probability human care alone could have produced and preserved the race of
dancers.

In answer to the question, how and when did the race of dancers originate,
it may be said that historical research indicates that a structural
variation or mutation which occasionally appears in _Mus musculus_, and
causes those peculiarities of movement which are known as dancing, has
been preserved and accentuated through selectional breeding by the Chinese
and Japanese, until finally a distinct race of mice which breeds true to
the dance character has been established. The age of the race is not
definitely known, but it is supposed to have existed for several