ACTIVITY OF THE ALBINO RAT 



33 



of curves in Fig. 12. The most noticeable thing in this figure 

 is the great difference existing between the males and the female. 

 They all kept fairly close together until the fifth month of age. 

 After this the female, No. 3, rapidly surpassed the males in 

 total amount and ended her life with a total run of 5447 miles. 

 This distance is nearly three and one-half times as great as 

 the average distance run by the males. In other words the 

 ratio of total activity of the male to the female was 1 :3-44. 



It seems almost incredible that a rat would run 5447 miles 

 during its lifetime. For this rat it was an average run of a 

 little less than 5.5 miles each day. During its very young days 

 and its old age it did not run this distance each day. Through- 

 out the prime of its life, however, it was no uncommon thing 

 for it to run 10 or 12 miles a day. The males averaged less 

 than two miles each day during their lifetime. Since the main 

 bulk of the activity was confined to the 12 hours from 3 p. m. 

 to 3 a. m. we can see that the rate of running for the female 

 averaged almost one-half mile each hour and for the males a 

 little less than one-sixth of a mile per hour of activity during 

 their lifetime. 



We have already said that the greatest amount of daily 

 activity was accomplished by the males at the age of 10 months 

 and by the females at the age of 12.5 months. What portion 

 of the total amount of work accomplished during their lifetime 

 had been performed at these ages? Table III shows not only 

 this but also the ages and the percentage equivalence of total 



TABLE III 



Percentage of Total Life Span Required to Do Certain Fractional Parts 

 of the Total Life's Work and the Age in Months at Which These 

 Amounts of Work Are Completed. 



