Malignant tumours of the bronchus were not recognised till comparatively recently. Adler, in 1912, is said to have been the first to report such a tumour. The great majority of new growths of the lung originate in the bronchi and subsequently invade the lung tissue. Primary carcinoma of the lung is not as rare as it used to be, for formerly it was said to occur in less than 1 per cent, of all primary carcinomas; but statistics from Hamburg and Leipzig reveal at times an incidence as high as 9-4 per cent, to 15-5 per cent., whilst Vinson, Moersch, and Kirklin have diagnosed Tj cases of primary carcinoma of the lung between 1925 and 1928, and Macrae, Funk and Jackson observed 13 cases and mentioned 128 cases reported by other authors.