Under the title “Is Cancer Mortality increasing or decreasing?” Wolff (1935) has discussed a problem of world-wide interest. He comes to the conclusion that, in German-speaking countries the risk of dying from cancer is not increasing in the sense that the ordinary man attaches to the phrase. He enquires whether the undoubted absolute increase in cancer mortality may not be a mere function of the ageing of the population, a feature common to all civilised countries; and he concludes that, for Berlin, the altered age structure of the population has caused the increase in the general rate of mortality from cancer, and that—taking certain other factors also into con sideration—it may fairly be concluded that in Berlin the rate of mortality from cancer has declined.