280 The Dancing Mouse 



sensitiveness to certain sounds. These differences at once 

 suggest the importance of an examination of the whirling 

 tendency of each line of descent. 



The results for the several generations of each line which 

 I had opportunity to examine are unexpectedly decisive so 

 far as the question in point is concerned. 



INDIVIDUALS OF THE 200 LINE 



MALES FEMALES 



First generation No. 200, ? No. 205, ? 



Second generation No. 210, Mixed whirler No. 215, Left whirler 



Third generation No. 220, Mixed whirler No. 225, Mixed whirler 



Fourth generation No. 230, Right whirler' No. 235, Mixed whirler 



Fifth generation No. 240, Right whirler No. 245, Left whirler 



INDIVIDUALS OF THE 400 LINE 



MALES FEMALES 



First generation No. 152, Left whirler No. 151, Left whirler 

 Second generation No. 410, Left whirler No. 415, Right whirler 

 Third generation No. 420, Left whirler No. 425, Left whirler 



One line of descent exhibited no pronounced whirling 

 tendency; the other exhibited a strong tendency to whirl to 

 the left. Are these statements true for the group of one hun- 

 dred individuals whose distribution among the three classes 

 of whirlers has been given? In order to obtain an answer 

 to this question I have reclassified these individuals accord- 

 ing to descent and direction of whirling. 



INDIVIDUALS OF THE 200 LINE 



RIGHT WHIRLERS LEFT WHIRLERS MIXED WHIRLERS TOTAL 



Males 7 6 8 21 



Females _ _8 8 21 



12 14 16 42 



