30 .(AMES ROLLIN SLONAKER 



than No. i, which was farthest away, would seem to indicate 

 that this supposed condition may have had its influence. Though 

 this supposition may be true, owing to the differences in the 

 curves of the two sexes, one is not justified in placing very much 

 credence in it. Other changes in their environment no doubt 

 are responsible to some extent for these fluctuations. This 

 will be discussed in more detail later. 



By comparing the figures in Table I and the curves in Fig. 1 1 

 a marked difference is observed in the average daily activity 

 of the two sexes. For the first four months there is not much 

 difference, but after this age the female excels the males to a 

 great extent, and is never equaled by them again. The greatest 

 average daily run as shown in this table was accomplished by 

 the female and consisted of 13002 revolutions, or a distance 

 of 1 1.2 miles. This same rat has a record of 14.2 miles during 

 24 consecutive hours. The greatest average daily run of any 

 of the males was 7574 revolutions, which was equivalent to 

 6.6 miles. The greatest average run for the four rats was at 

 the age of nine months. At the age of four months a uniform 

 and very marked rise in the curves is noticed, but as each rat 

 with the exception of No. 4 surpasses this amount of activity 

 at a later age this cannot be considered the age of greatest 

 activity. It is true, however, that the average for the males 

 alone is greater at this age than at any later time but it exceeds 

 by only a few revolutions. Hypothetical curves representing 

 the mean between the two extremes of activity for males and 

 females would show T the greatest amount of work for the males 

 at about the tenth month and for the female at about the age 

 of 12^ months. Owing to the fact that there was but one 

 female too much dependence cannot be placed on this result 

 since it was not an average. It is interesting to note, however, 

 that the ratio of the age of greatest activity (10 months) of the 

 males to the average age of their death (27 months) is 1:2.7 

 wdiich is practically the same as that for the female (12.5 months: 

 33.8 months) 1:2.7+. If this ratio can be depended upon, a 

 normal white rat would voluntarily do the greatest amount of 

 daily work at an age a little older than one-third that of its 

 whole normal life. It would be exceedingly interesting to 

 know if this ratio would apply to other animals. 



