10 CHARLES A. COBURN 



or it may not bite at all until it is teased whereupon it will do 

 so vigorously for an instant or two. 



Squeaking is an indication of a fairly high degree of savage- 

 ness unless the mouse is hurt, in which case it may be observed 

 where there is little or no savageness. 



Although the types of behavior mentioned above are the 

 chief indications of wildness and savageness in mice, a great 

 many others which are very significant often appear. The 

 range of individuality of mice, to the experienced observer, is 

 very great. In spite of these many indications and the differ- 

 ent degrees of intensity with which they appear in the behavior 

 of mice during a test, very rarely did the writer, after he had 

 had some experience, have difficulty in forming a judgment of 

 the grade of wildness or savageness observed. 



A description of the wild and tame mice used in this study 

 is given in table 1. 



The observations and tests made on the tame mice from the 

 Bussey Institute and Miss Abbie E. C. Lathrop for some time 

 after they arrived at the laboratory indicated in no case a grade 

 of wildness or savageness above 0. The mice from the Bussey 

 Institute were from a strain which had been in use there for 

 some time for various color and structural studies and were 

 from stock which had originally been obtained from Miss 

 Lathrop. After they had been used in the present study for 

 about a year, it was quite accidently learned that there was 

 some possibility of their possessing some wild blood as mice 

 from this strain had at various times been crossed with wild 

 in the color studies. In order to secure more definite informa- 

 tion a mating was made from these mice and the offspring tested. 

 The results are shown in table 2. 



The table gives in the upper left hand corner (a) the average 

 number of tests; {b) the range of tests; (c) the average age at 

 the time of the first test; (d) the average age for the last test; 

 immediately below, (e) the number of mice and sex; to the 

 right of this, (/) the average grade attained in the first test for 

 wildness; (g) the average of the first and second tests; {h) the 

 average of all the tests; (i) the average of the third, fourth and 

 fifth tests; (j) the average grade attained in the last test. Im- 

 mediately to the right of these averages is presented the dis- 

 tribution of the mice in the grades to 5. The averages for 



