Being an infective disease, tuberculosis comes into the same category as the infectious diseases. Large sums of money very properly are spent each year in the prevention of these diseases; hitherto but little has of set purpose been spent on measures for the prevention of tuberculosis. People may, therefore, with advantage consider, in the first place, the relative magnitude of these different causes of death. In the registrar-general's returns for England and Wales other diseases than those enumerated above are classified as infective, that is, produced by infection received from without. In 1904 the death-rate in England and Wales from phthisis was 1.46 per 1000 of population among males and 1.03 per 1000 among females. The significance of the different age distribution of the phthisis death-rate in the two sexes will be subsequently considered. Phthisis is not the only fatal disease due to tuberculous infection.