Thinking that Japanese literature might furnish more information bearing on the question of racial history than was available from European sources, I wrote to Professor Mitsukuri of the University of Tokyo, asking him whether any reliable records of the dancer existed in Japan. He replied as follows: "I have tried to find what is known in Japan about the history of the Japanese waltzing mice, but I am sorry to say that the results are wholly negative. I cannot find any account of the origin of this freak, either authentic or fictitious, and, strange as it may seem to you, no study of the mice in a modern sense has been made, so you may consider the literature on the mouse in the Japanese language as absolutely _nil_." In explanation of this somewhat surprising ignorance of the origin of the race in what is commonly supposed to be its native land, Professor Mitsukuri adds: "The breeders of the mice have mostly been ignorant men to whom writing is anything but easy." In response to similar inquiries, I received 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.