Among the different factors which may influence the peripheral needs for thyroid hormone, changes in environmental temperature seem to have been most extensively studied. Different workers in this field (Bondy et al., 1952, Leblond et al., 1952, Rand et al., 1952, Kassenaar et al., 1956) were able to show by different types of experiments, that prolonged exposure to low temperatures is accompanied by an increase in peripheral thyroxine requirement. Kassenaar et al. (1956) clearly showed that these experiments have preferably to be done on thyroidectomized, thyroxine maintained animals as compensatory action may mask the results when intact animals are used.
Contrary to this, very little is known about the influence of muscular exercise on the thyroxine disappearance rate: Bondy & Hagewood (1952) not only studied the effect of low temperatures, starvation and cortisone on the PBI
1. The first paper, on »The effect of environmental temperature on the blood protein