io The Dancing Mouse 



young, in which, however, none of the peculiarities of 

 behavior of the parents appeared. 



In view of this proof of the occurrence of dancing indi- 

 viduals among common mice, Saint Loup believes that the 

 race of dancers has resulted from the inheritance and ac- 

 centuation of an ''accidental" deviation from the usual mode 

 of behavior. It is scarcely necessary to say that this opinion 

 would be of far greater weight had he observed, instead of 

 postulating, the inheritance of the peculiarities of movement 

 which he has described. It might be objected, to the first of 

 his so-called facts, that the litter resulted from the mating 

 of mice which possessed dancer blood. Until the occurrence 

 of dancers among varieties of mice which are known to be 

 unmixed with true dancers is established, and further, until 

 the inheritance of this peculiar deviation from the normal 

 is proved, Saint Loup's account of the origin of the dancing 

 mouse race must be regarded as an hypothesis. 



The occurrence of dancing individuals among common mice 

 has been recorded by several other observers. Kammerer 

 (20 p. 389) reports that he found a litter of young wood 

 mice (Mus sylvaticus L.) which behaved much as do the 

 spotted dancers of China. He also observed, among a lot 

 of true dancers, a gray individual which, instead of spinning 

 around after the manner of the race, turned somersaults at 

 frequent intervals. It is Kammerer's opinion, as a result 

 of these observations, that the black and white dancers of 

 China and Japan have been produced by selectional breed- 

 ing on the basis of this occasional tendency to move in circles. 

 Among albino mice Rawitz (25 p. 238) has found individuals 

 which whirled about rapidly in small circles. He states, 

 however, that they lacked the restlessness of the Chinese 

 dancers. Some shrews (Sorex vulgaris L.) which exhibited 

 whirling movements and in certain other respects resembled 



