The Inheritance of Forms of Behavior 281 

 INDIVIDUALS OF THE 400 LINE 



RIGHT WHIRLERS LEFT WHIRLERS MIXED WHIRLERS TOTAL 



Males 4 9 i 14 



Females _6^ _p_ 4 19 



10 18 5 33 



25 



Three interesting facts are indicated by these results: 

 first, the inheritance of a tendency to whirl to the left in the 

 400 line of descent ; second, the lack of any definite whirling 

 tendency in the 200 line; and third, the occurrence of right 

 and left whirlers with equal frequency as a result of the cross- 

 ing of these two lines of descent. 



It is quite possible, and I am inclined to consider it prob- 

 able, that the pure dancer regularly inherits a tendency to 

 whirl to the left, and that this is obscured in the case of the 

 200 line by the influences of a cross with another variety of 

 mouse. It is to be noted that the individuals of the 200 line 

 were predominantly mixed whirlers, and I may add that 

 many of them whirled so seldom that they might more appro- 

 priately be classed as circlers. 



The white-black discrimination experiments which were 

 made in connection with the study of vision and the modi- 

 fiability of behavior were so planned that they should furnish 

 evidence of any possible tendency towards the inheritance 

 of modifications in behavior. The problem may be stated 

 thus. If a dancing mouse be thoroughly trained to avoid 

 black, by being subjected to a disagreeable experience every 



