ABSTRACT
The opinion that fat cells can sense and respond to temperature so as to provide a triglyceride mixture with a melting point just below the environmental temperature (Lands, 1965) is widely held. This view disregards the fact that the body fat of most marine animals, including homeotherms, is highly unsaturated and has melting points much below environmental temperatures, whereas the final melting point of beef tallow and lard may be considerably above body temperature. In the bat, brown adipose tissue fat is less saturated in the summer than during hibernation (Wells, Makita, Wells & Krutzsch, 1965). In hamsters, body fat becomes less saturated after cold exposure, but this effect may be only indirectly due to temperature, because the same effect results from semi-starvation or cortisone treatment at normal temperature (Kodama & Pace, 1963). Furthermore, the fatty acid composition of the diet may greatly affect the body-fat composition and influence the results obtained by variation of temperature.
