THERE will be few more interesting chapters in the history of science than that which includes the development of our knowledge of the chemistry and physiology of the thyroid gland. Prof. Harington's book offers an excellent basis for that chapter. He reviews early conceptions of the nature of thyroid function, the gradual defini tion of ideas through the study of myxœdema, operative and experimental removal of the gland, and replacement therapy, to Magnus Levy's demonstrations in 1895 of the characteristic effect of the thyroid on metabolism. The Thyroid Gland: its Chemistry and Physiology. By Prof. Charles Robert Harington. Pp. xiii + 222 + 8 plates. (London: Oxford University Press, 1933.) 15s. net.