BEHAVIORISTIC STUDY OF THE RAT 
19 
The determination of this critical point of activity might be 
of help to the physiologist in solving several of the problems of 
animal heat. Work in this field does not seem to have progressed 
very much since the nineties chiefly for the reason that the 
Fig. 10. Distribution of Spontaneous Activity in a High External 
Temperature 
Age of animals about 300 days 
