ACTIVITY OF THE ALBINO RAT 41 



By consulting Table V and Figs. 13 and 14 it is readily seen 

 that the greatest weight is attained at an earlier age by the 

 control rats than by the exercised ones. The control males 

 reached their greatest average weight of 320 grams at the aver- 

 age age of 391 days. It took the exercised male rats 534 days to 

 reach their average maximum weight of 262 grams. The differ- 

 ences in weights and ages at death are also very pronounced. 



Just how much work the control rats would have been able 

 to perform at a given age and how it would have compare'd 

 with that of the exercised rats at the same age can not be 

 stated as it was not tested. But it is generally conceded that 

 animals kept in close confinement, without a ready means of 

 exercise, can not perform as much work and are much less 

 agile than those having the chance of exercise. 



So far as health is concerned it appeared that both control 

 and exercised rats were in the best of physical condition. There 

 was, however, a marked difference in the general behavior and 

 attitude of the two groups. The control rats were slow in their 

 movements, sluggish in appearance and seemed to lack energy, 

 snap, and alertness. The exercised rats, on the other hand, were 

 the reverse in all these respects. They were quick and very 

 agile, bright in appearance, full of vim and very alert. Since 

 these two groups of animals had the same food and practically 

 the same environment it appears that the absence of a ready 

 means of exercise on the one hand and the presence of it on 

 the other is an important factor in causing this marked differ- 

 ence. Again the presence of exercise seems to be one of the 

 causes for the difference in length of life of the two groups. 

 Apparently the rats in the revolving cages not only used up 

 some of the energy in exercise which would have gone into 

 growth, but have also used up some of the energy which would 

 have lengthened their lives. 



A slight modification in the environment may probably have 

 been instrumental in causing a difference in the length of life, 

 possibly also of growth. The control rats were furnished with 

 a large bunch of excelsior which they would fashion into a nest. 

 The character of the nest depended upon the temperature. In 

 cold weather the nest would be completely surrounded and 

 covered over having a little tunnel for entrance, but in warm 

 weather it would be open at the top. In this manner of living 



