The left whirlers occur in excess of both the right and the mixed whirlers. This fact, together with the results which have already been considered in connection with the counts of turning, suggests that a tendency to whirl in a certain way may be inherited. I have examined my data and conducted breeding experiments for the purpose of ascertaining whether this is true. But as the results of this part of the investigation more properly belong in a special chapter on the inheritance of behavior (XVIII), the discussion of the subject may be closed for the present with the statement that the preponderance of left whirlers indicated above is due to a strong tendency to turn to the left which was exhibited by the individuals of one line of descent.
TABLE 4
AVERAGE NUMBER OF WHIRLS TO THE RIGHT AND TO THE LEFT FOR THE SIX INTERVALS OF TABLES 2 AND 3, WITH A CHARACTERIZATION OF THE ANIMALS AS RIGHT WHIRLERS, LEFT WHIRLERS, OR MIXED WHIRLERS.
AVERAGE NO. AVERAGE NO. MALES AGE OF WHIRLS OF WHIRLS CHARACTERIZATION
2 12 mo. 136.7 3.3 Right whirler
30 2 mo. 109.7 2.5 Right whirler
34 2 mo. 4.3 96.5 Left whirler
36 2 mo. 197.5 23.5 Right whirler
152 6 mo. 6.8 137.0 Left whirler
156 1 mo. 73.2 12.8 Right whirler
210 3 mo. 78.7 62.0 Mixed whirler
220 4 mo. 74.3 40.2 Mixed whirler
410 3 mo. 10.3 139.0 Left whirler
420 3 mo. 12.2 241.3 Left whirler
Average 70.4 75.8 4 Right whirlers 4 Left whirlers 2 Mixed whirlers
FEMALES
29 2 mo. 23.7 53.2 Left whirler 33 2 mo. 362.7 2.7 Right whirler 35 2 mo. 208.5 19.2 Left whirler 151 6 mo. 5.0 140.0 Right whirler 157 1 mo. 47.0 51.2 Left whirler 211 3 mo. 109.7 61.5 Right whirler 215 3 mo. 57.8 234.5 Mixed whirler 225 4 mo. 103.2 56.3 Mixed whirler 415 3 mo. 216.7 3.5 Left whirler 425 3 mo. 17.0 225.2 Left whirler
Average 115.1 84.7 3 Right whirlers 4 Left whirlers 3 Mixed whirlers
The tendency of the dancer's activity to increase in amount toward evening, which the results of Tables 2, 3, and 4 exhibit, demands further consideration. Haacke (7 p. 337) and Kishi (21 p. 458) agree that the dancing is most vigorous in the evening; but Alexander and Kreidl (i p. 544) assert, on the contrary, that the whirling of the individuals which they observed bore no definite relation to the time of day and apparently was not influenced in intensity thereby. Since the results of my own observations contradict many of the statements made by the latter authors, I suspect that they may not have watched their animals long enough to discover the truth. The systematic records which I have kept indicate that the mice remain quietly in their nests during the greater part of the day, unless they are disturbed or come out to obtain food. Toward dusk they emerge and dance with varying intensity for several hours. I have seldom discovered one of them outside the nest between midnight and daylight. The period of greatest activity is between 5 and 10 o'clock P.M.