The occurrence of dancing individuals among common mice has been recorded
by several other observers. Kammerer (20 p. 389) reports that he found a
litter of young wood mice (_Mus sylvaticus L_.) which behaved much as do
the spotted dancers of China. He also observed, among a lot of true
dancers, a gray individual which, instead of spinning around after the
manner of the race, turned somersaults at frequent intervals. It is
Kammerer's opinion, as a result of these observations, that the black and
white dancers of China and Japan have been produced by selectional
breeding on the basis of this occasional tendency to move in circles.
Among albino mice Rawitz (25 p. 238) has found individuals which whirled
about rapidly in small circles. He states, however, that they lacked the
restlessness of the Chinese dancers. Some shrews (_Sorex vulgaris L_.)
which exhibited whirling movements and in certain other respects resembled
the dancing mouse were studied for a time by Professor Haecker of Freiburg
in Baden, according to a report by von Guaita (17 p. 317, footnote).
Doctor G. M. Allen of Cambridge has reported to me that he noticed among a
large number of mice kept by him for the investigation of problems of
heredity[1] individuals which ran in circles; and Miss Abbie Lathrop of
Granby, Massachusetts, who has raised thousands of mice for the market,
has written me of the appearance of an individual, in a race which she
feels confident possessed no dancer blood, which whirled and ran about in
small circles much as do the true dancers.

[Footnote 1: Allen, G.M. "The Heredity of Coat Color in Mice." Proc. Amer.
Academy, Vol. 40, 59-163, 1904.]

Although it is possible that some of these cases of the unexpected
appearance of individuals with certain of the dancer's peculiarities of
behavior may have been due to the presence of dancer blood in the parents,