12 The Dancing Mouse 



normal, healthy or pathological? That the question cannot 

 be answered with certainty off-hand will be apparent after 

 we have considered the facts of structure and function which 

 this volume presents. 



Everything organic sooner or later is accounted for, in 

 some one's mind, by the action of natural selection. The 

 dancing mouse is no exception, for Landois (22 p. 62) thinks 

 that it is the product of natural selection and heredity, 

 favored, possibly, by selectional breeding in China. He 

 further maintains that the Chinese dancer is a variety of 

 Mus musculus L. in which certain peculiarities of behavior 

 appear because of bilateral defects in the brain. This author 

 is not alone in his belief that the brain of the dancer is de- 

 fective, but so far as I have been able to discover he is the 

 only scientist who has had the temerity to appeal to natural 

 selection as an explanation of the origin of the race. 



Milne-Edwards, as quoted by Schlumberger (29 p. 63), is 

 of the opinion that the Chinese dancer is not a natural wild 

 mouse race, but instead the product of rigid artificial selec- 

 tion. 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 



