Fig. 2. Thermolimit respirometry on an ant, Pogonomyrmex rugosus, mass 10.2 mg (run no. AFPR_011). Clearly visible on the _CO2 trace (left scale adjacent to graph; µl h^-1) are the seven stages of the ant's response: equilibration (1; ca. 0–10 min), ramping (2; ca. 10–36 min), premortal plateau (3; ca. 36–40 min), mortal fall (4; ca. 40–44 min), postmortal valley (5; ca. 45 min), postmortal peak (6; ca. 50 min) and exponential decay (7; >ca. 50 min) phases. See text for details and definitions. The equilibration temperature (right scale) was 44.84°C. The ramping rate was 0.254°C min^-1. The CT_max of this ant was 51.87°C (spiracular) and 51.68°C (locomotor), defined as the temperature at the breakpoint of the lag-corrected _CO2 ADS trace and the activity ADS trace, respectively. _CO2 begins with a brief baseline. The units of the activity ADS scale are arbitrary (left scale); the _CO2 ADS trace is similar and is not shown. Note that the absolute value of the ADS trace is shown; where activity is more intense (especially during the premortal plateau) the slope of the ADS trace vs. time increases dramatically, only to inflect to near zero at the theta point (see Fig. 3). Only the slopes vs. time of the ADS traces, and not their absolute magnitudes, were used for analysis.