MATERIALS AND APPARATUS 5 



No. I and No. 2 from litter A, and No. 3 and No. 4 from litter B, were 

 put into revolving cages to be used as omnivorous feeders in deter- 

 mining their activity; No, 5 and No. 6 from litter A, and No. 7 and 

 No. 8 from litter B, were put in revolving cages to be used in ascer- 

 taining the amount of work the vegetarian feeders would perform; No. 

 9 and No. 10 from litter A, and No. 11 and No. 12 from litter B, were 

 put in stationary cages for omnivorous controls; and No. 13 and No. 

 14 from litter A, and No. 15 and No. 16 from litter B, were placed in 

 stationary cages for vegetarian controls. Thus each litter was equally 

 and uniformly distributed. Unfortunately the sexes were not ideally 

 grouped. The following table illustrates the manner in which the 

 young were distributed. 



Omnivorous Exer- 



Vegetarian Exer- 



Omnivorous Control 



Vegetarian Control 



cised Rats 



cised Rats 



Rats 



Rats 



Litter 



No. 



I 



Sex 



Litter 



No. 



Sex 



Litter 



No. 



Sex 



Litter 



No. 



Sex 



A 



Male 



A 



S 



Male 



A 



Q 



Male 



A 



13 



Female 



" 



2 



(( 



" 



6 



Female 



" 



10 



" 



<{ 



14 



Male 



B 



3 



Female 



B 



7 



" 



B 



II 



Female 



B 



i,S 



11 



" 



4 



Male 



" 



8 



" 



** 



12 



Male 



" 



16 



a 



Each rat was thus confined in a cage by itself, which served as 

 its home for its entire lifetime, and from which it was taken at inter- 

 vals of about two weeks for a time sufficient to weigh the rat and 

 clean its cage. 



The apparatus for recording the activity has already been des- 

 cribed,* but may be briefly given again. It consisted of a series of 

 eight cylindrical cages which revolved on stationary axles to which 

 were attached the nest boxes. The food and water boxes were attached 

 to the ends of the nest boxes. The cage thus revolved about the sta- 

 tionary nest box whenever the rat ran. Automatic devices were attach- 

 ed to register the number of revolutions and to record them on paper 

 kept moving by a continuous roll kymograph. The first device being 

 read in the morning and in the evening gave the daily and nightly 

 run of each rat through its lifetime. The second arrangement showed 

 the distribution of the activity of each rat for each twenty-four hours 

 during its whole life. These records were of great assistance in show- 

 ing the peculiarities of activity which occurred at different ages. 



This apparatus was therefore only adapted to recording the run- 

 ning activity of the animals. Previous observations^ have shown that 

 the running activity of the rat is proportional to the other activities. 



