where C_{mw} is wet and C_{md} is dry conductance
(mL O_{2}.g^{-1}.h^{-1}. deg.C^{-1}); [.H]_{r} is the lowest resting
metabolic rate measured at each temperature (mL O_{2}.g^{-1}.h^{-1});
[.E]_{eq} is oxygen equivalent for heat lost by evaporation
[[.E]_{eq} = mL O_{2}.g^{-1}.h^{-1} = [.E].[lambda]/[gamma], where
[.E] is evaporative water loss (mg.g^{-1}.h^{-1}), [lambda] is heat of
vaporization for water (2.43 J/mg), and [gamma] is heat equivalent for
oxygen (20.097 J/mL)]; T_{b} is body temperature ( deg.C); and T_{a} is
chamber air temperature ( deg.C). Only data from animals equipped with
temperature-sensitive radio transmitters were used for these
calculations.
TABLE 3.--Minimum wet and dry thermal conductances
(mL O_{2}.g^{-1}.h^{-1}. deg.C^{-1}) of _Procyon lotor_ in summer
and winter. Means of values were calculated from equations 3
and 4 (s.d. = standard deviation and n = number of observations).
----------------------+----------------------------------------
| Thermal conductance
Season and sex |----------------------------------------
| Wet +-s.d. (n) Dry +-s.d. (n)
----------------------+----------------------------------------
Summer |
Captive, both sexes | 0.0256 +-0.0028 (18) 0.0246 +-0.0019 (12)
Winter |
Captive, female | 0.0172 +-0.0023 (10) 0.0161 +-0.0027 (6)
----------------------+----------------------------------------
[Illustration: FIGURE 2.--Relationship between oxygen consumption
and chamber air temperature for raccoons in summer: captive
females, open circles; captive males, closed circles; trapped
males, open squares. Sloping lines represent regressions of oxygen
consumption on chamber air temperature, and horizontal lines, basal
metabolism.]
[Illustration: FIGURE 3.--Relationship between oxygen consumption
and chamber air temperature for raccoons in winter: captive
females, open circles; captive males, closed circles. Solid sloping
line represents regression of oxygen consumption on chamber air
temperature for males and females, and the horizontal line, basal
metabolism for males and females.]
C_{mw} was calculated for each season from metabolic measurements made
at all air temperatures below T_{lc} (Table 3). Because evaporative
water loss was not measured at temperatures below freezing, C_{md}
was calculated only from metabolic determinations made at air
temperatures between T_{lc} and 0 deg.C. There was no difference
between males and females in summer for either C_{mw} or C_{md}
(mL O_{2}.g^{-1}.h^{-1}. deg.C^{-1}). Data for each sex were combined
to give a summer average of 0.0256 +-0.0028 for C_{mw}, and 0.0246
+-0.0019 for C_{md} (Table 3). These summer conductances were 49% higher
(p<0.005) than those calculated for winter females (0.0172 +-0.0023, and
0.0161 +-0.0027 for C_{mw} and C_{md}, respectively; Table 3). C_{mw} and
C_{md} were not different from each other in either summer or winter,
which indicated that in both seasons evaporative water loss contributed
very little to heat dissipation at temperatures below T_{n}. Comparisons
of thermal conductances calculated on the basis of metabolic body size
(Mellen, 1963) gave the same results.