The Dancing Mouse | Page 7

the following letter,
confirmatory of Professor Mitsukuri's statements, from Doctor S. Hatai
of Wistar Institute, Philadelphia: "If I remember rightly the so-called
Japanese dancing mouse is usually called by us _Nankin-nedzumi_.
Nankin means anything which has been imported from China, and
nedzumi means rat-like animal, or in this case mouse, or Chinese
mouse. I referred to one of the standard Japanese dictionaries and found
the following statement: 'The _Nankin-nedzumi_ is one of the varieties
of Mus spiciosus (_Hatszuka-nedzumi_), and is variously colored. It
was imported from China. These mice are kept in cages for the
amusement of children, who watch their play.' Mus spiciosus, if I
remember correctly, is very much like Mus musculus in color, size, and
several other characteristics, if not the same altogether."
In Swinhoe's list of the mammals of China, which appeared in the
Proceedings of the Zoological Society of London for 1870, Mus
musculus L. is mentioned as occurring in houses in South China and in
Formosa. It is further stated that black and white varieties which are
brought from the Straits are often kept by the Chinese (p. 637).
The statements of Kishi, Mitsukuri, and Hatai which have been quoted,
taken in connection with the opinions expressed by various European

scientists who have studied the dancer, make it seem highly probable
that the race appeared first in China, and was thence introduced into
Japan, from which country it has been brought to Europe and America.
Accepting for the present this conclusion with reference to the place of
origin of the dancer, we may now inquire, how and when did this
curious freak, as Professor Mitsukuri has called it, come into existence?
Concerning these matters there is wide divergence of opinion.
Haacke (6 p. 514), as quoted in Brehm's "Tierleben," says that an
animal dealer with whom he discussed the question of the possible
origin of the dancer maintained that it came from Peru, where it nests in
the full cotton capsules, arranging the cotton fibers in the form of a nest
by running about among them in small circles. Hence the name cotton
mouse is sometimes applied to it. Haacke himself believes, however,
that the race originated either in China or Japan as the result of
systematic selectional breeding. Of this he has no certainty, for he
states that he failed to find any literature on the "beautiful mice of
China and Japan." Whether Haacke's description of the dancing mouse
was published elsewhere previous to its appearance in Brehm's
"Tierleben" I am unable to state; I have found nothing written on the
subject by him before 1890. Zoth (31 p. 176) also thinks that the race
was developed by systematic breeding, or in other words, that it is a
product of the skill of the Asiatic animal breeders.
Another account of the origin of the race is that accepted by Kishi (21 p.
481) and some other Japanese biologists. It is their belief that the forms
of movement acquired by the individual as the result of confinement in
narrow cages are inherited. Thus centuries of subjection to the
conditions which Kishi has described (p. 6) finally resulted in a race of
mice which breed true to the dance movement. It is only fair to add,
although Kishi does not emphasize the fact, that in all probability those
individuals in which the dancing tendency was most pronounced would
naturally be selected by the breeders who kept these animals as pets,
and thus it would come about that selectional breeding would
supplement the inheritance of an acquired character. Few indeed will be
willing to accept this explanation of the origin of the dancer so long as
the inheritance of acquired characters remains, as at present, unproved.

Still another mode of origin of the mice is suggested by the following
facts. In 1893 Saint Loup (28 p. 85) advanced the opinion that dancing
individuals appear from time to time among races of common mice.
The peculiarity of movement may be due, he thinks, to an accidental
nervous defect which possibly might be transmissible to the offspring
of the exceptional individual. Saint Loup for several months had under
observation a litter of common mice whose quick, jerky, nervous
movements of the head, continuous activity, and rapid whirling closely
resembled the characteristic movements of the true dancers of China.
He states that these mice ran around in circles of from 1 to 20 cm. in
diameter. They turned in either direction, but more frequently to the left,
that is, anticlockwise. At intervals they ran in figure-eights ([Symbol:
figure eight]) as do the true dancers. According to Saint Loup these
exceptional individuals were healthy, active, tame, and not markedly
different in general intelligence from the ordinary mouse. One of these
mice produced a litter of seven young, in which, however, none of