Fig. 4. Brain temperature as a function of carotid blood temperature (Ai–Di), and frequency distribution of blood temperature (Aii–Dii), in four ostriches. The 5 min values of blood temperature were sorted into classes of 0.1°C width. Values in Ai–Di are means ± S.D. and minima and maxima of brain temperature at each class of blood temperature. Aii–Dii show absolute frequencies at which each class of blood temperature occurred; N=2304 data points for ostrich 1 (A), 1728 for ostrich 3 (B), 1440 for ostrich 5 (C) and 4032 for ostrich 4 (D). The lines of identity of brain and blood temperatures are shown in Ai–Di.