The Inheritance of Forms of Behavior 279 



plete turns in five-minute intervals at six different hours of 

 the day. For the remaining eighty individuals the direction 

 was discovered by observation of the activity of the animals 

 for a brief interval at five different times. Naturally, the 

 former results are the more exact; in fact, they alone have 

 any considerable quantitative value. But for the problem 

 under consideration all of the determinations are sufficiently 

 accurate to be satisfactory. 



The distribution of the individuals which were examined as 

 to direction of whirling is as follows. 



RIGHT WHIRLERS LEFT WHIRLERS MIXED WHIRLERS TOTAL 

 Males 19 19 12 50 



Females 12 23 15 50 



The frequency of occurrence of left whirlers among the 

 females is unexpectedly high. Is this to be accounted for 

 in terms of inheritance ? In my search for an answer to this 

 question I followed the whirling tendency from generation 

 to generation in two lines of descent. These two groups of 

 mice have already been referred to as the 200 line and the 

 400 line. The former were descended from Nos. 200 and 

 205, and the latter from Nos. 152 and 151. Individuals 

 which resulted from the crossing of these lines will be referred 

 to hereafter as of mixed descent. There were some striking 

 differences in the behavior of the mice of the two lines of 

 descent. As a rule the individuals of the 200 line climbed 

 more readily, were more active, danced less vigorously, 

 whirled less rapidly and less persistently, and were in several 

 other respects much more like common mice than were the 

 individuals of the 400 line. It is also to be noted (see Table 

 5, p. 89) that few of the litters of the 200 line exhibited 

 auditory reactions, whereas almost all of the litters of the 

 400 line which were tested gave unmistakable evidence of 



