TEMPERAMENTAL DIFFERENCES IN ALBINO RATS 



117 



the animals in the cage and their relation to one another may 

 be stated thus: 



(1) Outbred individuals more frequently come forward in the 

 cage than inbred. 



(2) Females more frequently come forward than males. 



(3) Individual differences are greater than are the differences 

 between the two strains or the two sexes. 



(4) Inbred males and females are found together 3 times as 

 frequently as are outbred males and females. 



ACTIVITY 



The degree of activity of the several rats, as indicated by 

 their walking, running, climbing, washing, sniffing, seeking for 

 food, lifting the lid of the cage, and so on, was observed and 

 roughly graded by means of the numerals to 5, indicating 

 minimum activity and 5 maximum activity. 



As in the previous case, tabular presentation is possible, and 

 in table 2 appear the comparable data for the two strains. In 

 this table, the numerator of the fraction is the sum of the various 

 grades given an animal in the total number of observations, 

 which appears as the denominator of the fraction. The average 

 grade in decimals in each case follows the fraction. 



TABLE 2 

 Amount of Activity of Rats 



Outbred 

 Date No. of rat Activity 



286 

 Oct. 15 on.... 251 O 1 .... — = 2.6 



110 

 221 



....253 " .... = 2.2 



100 



145 



Mar. 2 on.... 261 ".... = 2.4 



60 



103 



....263 " .... = 1.7 



60 

 94 



....265 " .... = 1.6 



60 



Inbred 

 Date No. of rat Activity 



163 

 Oct. 15 on. . . .201 (? — = 1.5 



110 



103 



....203 " .... = .9 



120 



66 

 Mar. 2 on. . . .211 " ....-- = 2.2 



30 



59 



" .. .213 "... . = 2.0 



30 

 70 



215 " ... . = 2.3 



30 



