The radiation behaviour of the molecules in a detuned cavity has been treated with a more rigorous method of quantum mechanics. The experimental finding of Higa, that when the deutuning of the first cavity reaches a critical value, the second cavity suddenly breaks out into oscillations at the centre frequency of the molecules, is interpreted. A formula is obtained for the critical detuning which leads to the sudden oscillation. The experimental curves obtained by Страховский and Татренков about the dependence of the radiation power of the molecules in the second cavity on the frequency detuning is qualitatively interpreted.