io8 



A. O. WEESE. 



TABLE III. 



SHOWING THE REACTIONS OF Phrynosoma IN A GRADIENT OF TEMPERATURE OF THE 



SUBSTRATUM. 



Temperatures are indicated at the tops of columns. Readings were taken at 

 intervals of one minute. In Experiment 27 the figures in italics indicate burrowing 

 on the part of the number of individuals so designated. For discussion see page 107. 



restless as the temperature of the soil approached 40. Most of 

 the animals burrowed, or at least flattened their bodies close to 

 the substratum as the surface temperature reached two or three 



