The Dancing Mouse | Page 9

Chinese dancer is not a natural wild mouse race, but
instead the product of rigid artificial selection. And in connection with
this statement Schlumberger describes a discovery of his own which
seems to have some bearing upon the problem of origin. In an old
Japanese wood carving which came into his possession he found a
group of dancing mice. The artist had represented in minute detail the
characteristics of the members of the group, which consisted of the
parents and eight young. The father and mother as well as four of the
little mice are represented as white spotted with black. Of the four
remaining young mice, two are entirely black and two entirely white.
The two pure white individuals have pink eyes, as has also the mother.
The eyes of all the others are black. From these facts Schlumberger
infers that the dancer has resulted from the crossing of a race of black
mice with a race of albinos; the two original types appear among the
offspring in the carving.
Experimental studies of the inheritance of the tendency to dance are of
interest in their bearing upon the question of origin. Such studies have

been made by Haacke (19), von Guaita (17, 18), and Darbishire (13, 14,
15, 16), and the important results of their investigations have been well
summarized by Bateson (5).
By crossing dancing mice with common white mice both Haacke and
von Guaita obtained gray or black mice which are very similar to the
wild house mouse in general appearance and behavior. The
characteristic movements of the dancers do not appear. As the result of
a long series of breeding experiments, Darbishire (16 pp. 26, 27) says:
"When the race of waltzing mice is crossed with albino mice which do
not waltz, the waltzing habit disappears in the resulting young, so that
waltzing is completely recessive in Mendel's sense; the eye-color of the
hybrids is always dark; the coat-color is variable, generally a mixture of
wild-gray and white, the character of the coat being distinctly
correlated with characters transmitted both by the albino and by the
colored parent." When hybrids produced by the cross described by
Darbishire are paired, they produce dancers in the proportion of about
one to five.
Bateson (5 p. 93, footnote), in discussing the results obtained by
Haacke, von Guaita, and Darbishire, writes: "As regards the waltzing
character, von Guaita's experiments agree with Darbishire's in showing
that it was always recessive to the normal. No individual in F1 [thus the
first hybrid generation is designated] or in families produced by
crossing F1 with the pure normal, waltzed. In Darbishire's experiments
F1 x F1 [first hybrids mated] gave 8 waltzers in 37 offspring, indicating
1 in 4 as the probable average. From von Guaita's matings in the form
DR x DR the totals of families were 117 normal and 21 waltzers....
There is therefore a large excess of normals over the expected 3 to 1.
This is possibly due to the delicacy of the waltzers, which are certainly
much more difficult to rear than normals are. The small number in von
Guaita's litters makes it very likely that many were lost before such a
character as this could be determined."
Bateson does not hazard a guess at the origin of the dancer, but merely
remarks (5 p. 86) that the exact physiological basis of the dancing
character is uncertain and the origin of this curious variation in

behavior still more obscure. "Mouse fanciers have assured me," he
continues, "that something like it may appear in strains inbred from the
normal type, though I cannot find an indubitable case. Such an
occurrence may be nothing but the appearance of a rare recessive form.
Certainly it is not a necessary consequence of inbreeding, witness von
Guaita's long series of inbred albinos." (von Guaita (17 p. 319) inbred
for twenty-eight generations.)
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