14 The Dancing Mouse 



Guaita's matings in the form DR x DR the totals of families 

 were 117 normal and 2 1 waltzers. . . . There is therefore a 

 large excess of normals over the expected 3 to i. This is 

 possibly due to the delicacy of the waltzers, which are cer- 

 tainly 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 in- 

 formation 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: (i) origin by selec- 

 tional 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 selec- 

 tion, 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 



