Metabolic rate and thermal insulation in albino and hairless mice

1. Rates of oxygen consumption of albino and hairless mice were measured in a metabolism chamber during periods of approximately 5 or 24 hr. Rectal temperature was measured before and after each period. The chamber temperatures used were 22, 30 and 32° C for both albino and hairless, and in addition 34 and 36° C for the hairless mice. 2. The mean age and body weight of the albino mice were 102 days and 34·6 g; the corresponding values for the hairless mice were 87 days and 32·8 g. 3. The mean minimum rates of oxygen consumption (ml./kg.min) were 31·0 for the albino and 38·8 for the hairless mouse; the corresponding estimated critical temperatures were in the ranges 30–32° C for the albino mouse and 32–34° C for the hairless mouse. 4. The mean values for core‐ambient thermal insulation (° C.m 2 .hr/kcal) were 0·418 and 0·328 for the albino mouse, and 0·275 and 0·221 for the hairless mouse, at 22 and 30° C respectively in each case.