HEREDITY OF WILDNESS AND SAVAGENESS IN MICE 37 



each of the three sets of groups (numbered for sake of conveni- 

 ence, 1,2, and 3), it is to be noted that this difference in Group 

 2 of the first and third set is greater than the difference in the 

 corresponding Group 1, while in the second set the reverse is 

 true. In other words, with the older mice, whether they are 

 from Fib or Fob, the decrease in grade of wildness and savage- 

 ness is greater when the mice are tested every day than when 

 they are tested at intervals of six or eight days, but with the 

 younger mice the daily testing shows the lesser decrease. 



When, however, the decreases are considered from the dif- 

 ferences of the averages of tests one and of tests three, four 

 and five, the results are uniform in all three sets of groups, 

 that is, the results in the first and third set are reversed and 

 in each set the tests given at intervals of 6 or 8 days show a 

 greater decrease in the grades of wildness and savageness than 

 in the case of the daily testing. It is the opinion of the writer 

 that the difference between the average of the first and second 

 tests and the third, fourth and fifth tests forms the more ac- 

 curate basis for the judgment of the rate of lowering of the 

 grades of wildness and savageness, since the effect of an error 

 in testing is thus minimized. 



Assuming that a test has an equal effect in lowering the grade 

 of wildness or savageness of the mice in Group 1 and Group 

 2, from the results in table 24 it is possible to obtain an approxi- 

 mate estimate of the effect of age plus the effect of the presence 

 of the experimenter in the room while feeding, cleaning cages 

 and testing other mice. For instance, in the case of Group 

 1, Fib, 0.47 grade represents the lessening of wildness due to 

 the effect of five testings, plus 30.28 days of age and the pres- 

 ence of the experimenter during that time. From Group 2, 

 Fib, it is observed that 0.29 grade represents the lessening of 

 wildness due to the effect of five testings, plus 4.93 days of age 

 and the effect of the presence of the experimenter. Subtract- 

 ing the results of Group 2 from those of Group 1, there is a 

 remainder of 0.18 grade which represents the lessening of the 

 wildness due to the effects of 25.35 days of age and the presence 

 of the experimenter during that time. In the same way the 

 lessening in savageness for the same reasons is found to be 0.85 

 grade. By dividing the amount of decrease by the number 

 of days are obtained the rates of decrease per day which in 



