ACTIVITY OF THE ALBINO RAT 21 



ing cages to ascertain their normal activity as manifested by 

 voluntary running. The remaining four (9, 10, 11 and 12) 

 were used for controls and were placed in stationary cages in 

 which rats are usually kept. In every case each rat was in a 

 cage by itself. This was its home during its life from which it 

 was removed only for a time sufficient to weigh the animal and 

 clean its cage. It was later ascertained that in this selection 

 six males and two females had been chosen. Fortunately three 

 males and one female comprised each of these two groups of 

 four. Numbers 1, 2, 4, 9, 10 and 12 were males; 3 and 11 were 

 females. 



The apparatus used for recording the activity has been pre- 

 viously described. 2 In brief it consisted of a large cylindrical 

 cage which revolved on a stationary axle. On the axle was 

 fastened the nest box, the food box and the water pan. The 

 cage revolved only when the rat ran. The number of revolu- 

 tions were automatically registered and at the same time each 

 revolution was automatically marked on paper kept moving by 

 a continuous roll kymograph. By the first device the exact 

 number of revolutions in a given time or the total number 

 could be readily ascertained for each rat. By the second con- 

 trivance the distribution and length of periods of activity and 

 rest during the day, night and lifetime could be consulted and 

 compared at any time. This graphic representation of the 

 activity has been of great assistance as only by this means do 

 the characteristics of the activity due to different ages appear. 



Only that phase of the activity of the rat manifested in vol- 

 untary running has been considered in this research. It was 

 impossible with this apparatus to record any of the other activi- 

 ties. However, numerous observations of the activities of the 

 rat readily convinces one of the fact that though running is 

 only one phase of activity it goes hand in hand with and is 

 directly proportional to the other activities. That is, if a rat 

 is in general very active at a given age it does a great deal of 

 voluntary running which has an apparent definite ratio to the 

 other activities. For this reason this one phase of the normal 

 daily activity has been taken as an indicator of all the activities 

 of an individual. 



2 Slonaker, J. R. Description of an apparatus for recording the activity of 

 small mammals. The Anat. Record, June, 1908, vol. 2, pp. 116-122. 



