A review of the literature indicates that the incidence of primary bronchiogenic carcinoma has shown a definite increase in recent years. The increase has been shown to have occurred not only in the United States and Canada but in the various European countries as well, particularly Germany. Pässler in 1896 collected fifty-seven cases of cancer of the lung, as compared with Adler, who in a study made in 1912 was able to collect 360 cases from the literature. In his study Adler stated that failure to recognize this type of tumor had for a long time sustained the belief that it is a rare condition. INCIDENCE Klotz1cited the literature showing the varying incidence of primary bronchiogenic carcinoma found by observers in succeeding periods. Thus Rheinhardt in 1878 noted cancer of the lung in 0.057 per cent of all autopsies; Fuchs in 1885 observed it in 0.065 per cent,