The Caloric Equilibrium of the Chicken Embryo

IN MAMMALS, the heat, produced by the foetus, is given off to the maternal tissues and the temperature of the foetus will be about the same as that of the pregnant animal. Exact figures on foetal temperature, heat production and caloric equilibrium are lacking in the literature; a survey of what is known about the metabolism of mammalian foetuses is given by Needham (1931), by Barcroft (1946) and by Brody (1945). The relatively low metabolic rate of the mammalian foetus is in accordance with the fact that it has no cooling surface and therefore no necessity to keep up its body temperature. (Barcroft, 1936). In caloric values, the mammalian foetus as a whole is about equal to a corresponding amount of maternal tissue. The dissipation of heat from the foetus to the mother takes place by the way of conduction and convection, the first via the surrounding medium of …