HEREDITY OF WILDNESS AND SAVAGENESS IN MICE 



nated on the outside of the cages and a description of each 

 mouse was taken at the time of the first test, no difficulty was 

 ever experienced in determining the identity of any mouse 

 which had escaped from its cage. It may be mentioned that 

 it w^as necessary to make the rooms occupied by the mice 

 rat proof as well as mouse proof. In the beginning sufficient 

 caution was not taken in this respect the result being that 

 many mice were killed by rats and others lost by escaping from 

 the room after they had by some chance escaped from their 

 cage. 



The following Is the record of the initial test of one litter. 

 The records of the subsequent tests were kept similarly ex- 

 cept the omission of the description of the mice and the num- 

 ber of their parents. 



June IS, 1913. F3's from F2 409 9 and F2 440 d'. Born April 29, 1913 



The types of behavior which were considered the chief indi- 

 cations of wildness In mice and were relied upon as a basis for 

 grading were as follows. 



1. Hiding from view In the cage just before the test or im- 

 mediately after, and attempts to hide from view in the hand 

 during the test. A wild mouse, though It may be feeding in 

 the open in the cage while the experimenter is moving about 

 the room or standing before the cage, will scurry to the back 

 of the cage and hide in the nest at the first move of the experi- 

 menter to open the door of the cage. A tame mouse, on the 

 other hand, will continue eating and is easily caught, in fact, it 

 will rarely make any attempt to prevent it. When the wild 

 mouse has been caught it is continually trying to find some 

 crevice between the fingers in which it may hide. If it succeeds 

 in covering its head it will often remain perfectly quiet as long 

 as it Is allowed to maintain this position. 



2. Running and jumping excitedly about the cage just before 

 being caught and attempts to escape from the hand after being 



