ADAPTATIONS TO DESEETS 



10 15 20 25 30 35 40 



AMBIENT TEMPERATURE °C 



Figure 7. Metabolic rate at different ambient temperatures expressed as per- 

 centage of basal values for three species of rodents: the arctic lemming (Scholander 

 et al., 1950), the nocturnal kangaroo rat( Dipodomys merriami) (unpublished observa- 

 tions, Carpenter, 1961), and the diurnal ground squirrel ( Citellus leucurus ) (Hudson; 

 1960). 



435 



