Differences in Behavior 277 



does the male upon the internal, organic changes which are 

 wrought by acts. At any rate the female seems to follow a 

 labyrinth path more mechanically, more accurately, more 

 easily, and with less evidence of sense discrimination than 

 does the male. 



Finally, in concluding this chapter, I may add that in those 

 aspects of behavior which received attention in the early 

 chapters of this volume the dancers differ very markedly. 

 Some climb readily on vertical or inclined surfaces to which 

 they can cling ; others seldom venture from their horizontally 

 placed dance floor. Some balance themselves skillfully on 

 narrow bridges; others fall off almost immediately. My 

 own observations, as well as a comparison of the accounts 

 of the behavior of the dancer which have been given by Cyon, 

 Zoth, and other investigators, lead me to conclude that there 

 are different kinds of dancing mice. This may be the result 

 of crosses with other species of mice, or it may be merely an 

 expression of the variability of an exceptionally unstable 

 race. 



I can see no satisfactory grounds for considering the dancer 

 either abnormal or pathological. It is a well-established 

 race, with certain peculiarities to which it breeds true; and 

 no pathological structural conditions, so far as I have been 

 able to learn, have been discovered. 



I have presented in this chapter on differences a program 

 rather than a completed study. To carry out fully the lines 

 of work which have been suggested by my observations and 

 by the presentation of results would occupy a skilled observer 

 many months. I have not as yet succeeded in accomplishing 

 this, but my failure is not due to lack of interest or of effort. 



