Abstract
Using histochemical techniques it has been demonstrated that the adrenal glands of baby rabbits lack noradrenaline and produce only adrenaline, while the adrenal glands of the pigeon contain oth adrenaline and noradrenaline and the relative proportion of noradrenaline secreting cells is almost the same as that of the adrenaline secreting cells. On exposure to higher ambient temperature there is release of adrenaline from the adrenal glands of baby rabbits and of both adrenalin and noradrenaline from the adrenal glands of pigeons. The possible role of the hypothalamus and the sympathetic nervous system in this response is discussed.