Characteristics, Origin, and History 1 1 



the dancing mouse were studied for a time by Professor 

 Hacker of Freiburg in Baden, according to a report by von 

 Guaita (17 p. 317, footnote). Doctor G. M. Allen of Cam- 

 bridge has reported to me that he noticed among a large 

 number of mice kept by him for the investigation of problems 

 of heredity * individuals which ran in circles ; and Miss 

 Abbie Lathrop of Granby, Massachusetts, who has raised 

 thousands of mice for the market, has written me of the ap- 

 pearance of an individual, in a race which she feels confident 

 possessed no dancer blood, which whirled and ran about in 

 small circles much as do the true dancers. 



Although it is possible that some of these cases of the 

 unexpected appearance of individuals with certain of the 

 dancer's peculiarities of behavior may have been due to 

 the presence of dancer blood in the parents, it is not at 

 all probable that this is true of all of them. We may, there- 

 fore, accept the statement that dancing individuals now and 

 then appear in various races of mice. They are usually 

 spoken of as freaks, and, because of their inability to thrive 

 under the conditions of life of the race in which they happen 

 to appear, they soon perish. 



Another and a strikingly different notion of the origin of 

 the race of dancers from those already mentioned is that of 

 Cyon (up. 443) who argues that it is not a natural variety 

 of mouse, as one might at first suppose it to be, but instead 

 a pathological variation. The pathological nature of the 

 animals is indicated, he points out, by the exceptionally high 

 degree of variability of certain portions of the body. Ac- 

 cording to this view the dancing is due to certain pathological 

 structural conditions which are inherited. Cyon's belief 

 raises the interesting question, are the mice normal or ab- 



1 Allen, G. M. "The Heredity of Coat Color in Mice." Proc. Amer. 

 Academy, Vol. 40, 59-163, 1904. 



