TEMPERAMENTAL DIFFERENCES IN ALBINO RATS 129 



inbred males, average 18.0; outbred females, average 19.4; 

 inbred females, average 18.2. 



(5) Individual and sex differences greatly exceed strain dif- 

 ferences. 



CONCLUSIONS 



The outbred and inbred strains of albino rats contrast in 

 temperament as follows: 



(1) Inbred males and females are found together in the cage 

 about three times as frequently as are outbred. 



(2) The inbred rats come forward in the cage on the approach 

 of the experimenter much less frequently than do the outbred. 



(3) Inbred rats are less active than outbred. 



(4) The inbred stock exhibits savageness by biting to approx- 

 imately twice the extent of the outbred. 



(5) The inbred animals respond more quickly and in greater 

 amount to momentary auditory stimulation than the outbred. 



(6) The two strains differ also in restlessness or continuity 

 of response. For the inbred restlessness is greatest in case of 

 momentary and repeated auditory stimulation and less in case 

 of continuous stimulation, whereas for the outbred animals, the 

 reverse is true. 



(7) The data indicate less difference between the sexes in the 

 inbred than the outbred rats. 



